docs: raspberrypi: Correct capitalization of Pico

In the context of Raspberry Pi's product line, this is Pico, not PICO.

Signed-off-by: Andrew Featherstone <[email protected]>

Author: ajf58

drivers/spi/Kconfig.rpi_pico

@@ -2,11 +2,11 @@
 # SPDX-License-Identifier: Apache-2.0
 
 config SPI_RPI_PICO_PIO
-	bool "Raspberry Pi PICO PIO SPI controller driver"
+	bool "Raspberry Pi Pico PIO SPI controller driver"
 	default y
 	depends on DT_HAS_RASPBERRYPI_PICO_SPI_PIO_ENABLED
 	select PICOSDK_USE_PIO
 	select PICOSDK_USE_CLAIM
 	select PINCTRL
 	help
-	  Enable driving SPI via PIO on the PICO
+	  Enable driving SPI via PIO on the Pico