Fix UART::write(const uint8_t *, ...) return size

[manchoz]

The UART::write(const uint8_t* c, size_t len) method now returns the actual number of written bytes.

Tested in production on Project Challenge Board (Arduino Edge Control).

[sebromero]

LGTM

[github-actions]

Memory usage change @ a570a64

Board	flash	%	RAM for global variables	%
arduino-beta:mbed:envie_m4	0 - 0	0.0 - 0.0	0 - 0	0.0 - 0.0
arduino-beta:mbed:envie_m7	🔺 0 - +64	0.0 - +0.01	0 - 0	0.0 - 0.0
arduino-beta:mbed:nano33ble	0 - 0	0.0 - 0.0	0 - 0	0.0 - 0.0

Click for full report table

Board	libraries/Scheduler/examples/MultipleBlinks flash	%	libraries/Scheduler/examples/MultipleBlinks RAM for global variables	%	libraries/doom/examples/Doom flash	%	libraries/doom/examples/Doom RAM for global variables	%	libraries/KernelDebug/examples/KernelDebug flash	%	libraries/KernelDebug/examples/KernelDebug RAM for global variables	%	libraries/Portenta_SDCARD/examples/TestSDCARD flash	%	libraries/Portenta_SDCARD/examples/TestSDCARD RAM for global variables	%	libraries/Portenta_System/examples/PortentaH7_getBootloaderInfo flash	%	libraries/Portenta_System/examples/PortentaH7_getBootloaderInfo RAM for global variables	%	libraries/Portenta_System/examples/PortentaH7_updateBootloader flash	%	libraries/Portenta_System/examples/PortentaH7_updateBootloader RAM for global variables	%	libraries/Portenta_Video/examples/Envie_video_coreboot flash	%	libraries/Portenta_Video/examples/Envie_video_coreboot RAM for global variables	%	libraries/Portenta_Audio/examples/PortentaAudioMicPDM flash	%	libraries/Portenta_Audio/examples/PortentaAudioMicPDM RAM for global variables	%	libraries/ThreadDebug/examples/ThreadDebug flash	%	libraries/ThreadDebug/examples/ThreadDebug RAM for global variables	%	libraries/USBHOST/examples/KeyboardController flash	%	libraries/USBHOST/examples/KeyboardController RAM for global variables	%	libraries/USBHOST/examples/Shell flash	%	libraries/USBHOST/examples/Shell RAM for global variables	%	libraries/PDM/examples/PDMSerialPlotter flash	%	libraries/PDM/examples/PDMSerialPlotter RAM for global variables	%
arduino-beta:mbed:envie_m4	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0
arduino-beta:mbed:envie_m7	0	0.0	0	0.0	64	0.01	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0	0	0.0
arduino-beta:mbed:nano33ble	0	0.0	0	0.0																													0	0.0	0	0.0									0	0.0	0	0.0

Click for full report CSV

Board,libraries/Scheduler/examples/MultipleBlinks<br>flash,%,libraries/Scheduler/examples/MultipleBlinks<br>RAM for global variables,%,libraries/doom/examples/Doom<br>flash,%,libraries/doom/examples/Doom<br>RAM for global variables,%,libraries/KernelDebug/examples/KernelDebug<br>flash,%,libraries/KernelDebug/examples/KernelDebug<br>RAM for global variables,%,libraries/Portenta_SDCARD/examples/TestSDCARD<br>flash,%,libraries/Portenta_SDCARD/examples/TestSDCARD<br>RAM for global variables,%,libraries/Portenta_System/examples/PortentaH7_getBootloaderInfo<br>flash,%,libraries/Portenta_System/examples/PortentaH7_getBootloaderInfo<br>RAM for global variables,%,libraries/Portenta_System/examples/PortentaH7_updateBootloader<br>flash,%,libraries/Portenta_System/examples/PortentaH7_updateBootloader<br>RAM for global variables,%,libraries/Portenta_Video/examples/Envie_video_coreboot<br>flash,%,libraries/Portenta_Video/examples/Envie_video_coreboot<br>RAM for global variables,%,libraries/Portenta_Audio/examples/PortentaAudioMicPDM<br>flash,%,libraries/Portenta_Audio/examples/PortentaAudioMicPDM<br>RAM for global variables,%,libraries/ThreadDebug/examples/ThreadDebug<br>flash,%,libraries/ThreadDebug/examples/ThreadDebug<br>RAM for global variables,%,libraries/USBHOST/examples/KeyboardController<br>flash,%,libraries/USBHOST/examples/KeyboardController<br>RAM for global variables,%,libraries/USBHOST/examples/Shell<br>flash,%,libraries/USBHOST/examples/Shell<br>RAM for global variables,%,libraries/PDM/examples/PDMSerialPlotter<br>flash,%,libraries/PDM/examples/PDMSerialPlotter<br>RAM for global variables,%
arduino-beta:mbed:envie_m4,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0
arduino-beta:mbed:envie_m7,0,0.0,0,0.0,64,0.01,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0,0,0.0
arduino-beta:mbed:nano33ble,0,0.0,0,0.0,,,,,,,,,,,,,,,,,,,,,,,,,,,,,0,0.0,0,0.0,,,,,,,,,0,0.0,0,0.0