Fix compilation against recent IDF (DDR for SD_MMC)

[muojp]

Hi. Compiling current Arduino-ESP32 (a0f0bd9) against current ESP-IDF (espressif/esp-idf@e54f3d9) fails due to the newly added SD_MMC DDR support on ESP-IDF: espressif/esp-idf@78fab8a0f .

Error:

C:/msys32/home/muo/esp/blink/components/arduino/libraries/SD_MMC/src/SD_MMC.cpp: In member function 'bool fs::SDMMCFS::begin(const char*, bool)':
C:/msys32/home/muo/esp/blink/components/arduino/libraries/SD_MMC/src/SD_MMC.cpp:59:5: sorry, unimplemented: non-trivial designated initializers not supported
     };
     ^
<snip>
C:/msys32/home/muo/esp/blink/components/arduino/libraries/SD_MMC/src/SD_MMC.cpp:59:5: warning: missing initializer for member 'sdmmc_host_t::command_timeout_ms' [-Wmissing-field-initializers]

This pull-req is a simple fix for this issue which syncs initializers with current code.

[me-no-dev]

there are far more issues than this now :) check this branch out: https://github.com/espressif/arduino-esp32/tree/idf-update

[me-no-dev]

Changes are merged :)

[muojp]

Great to hear that. Will test the branch later.