ev11l78a: initial import of the UPD301C Basic Sink board.

This board is a relatively inexpensive development kit for USB-PD
controllers, using an UPD301C controller.

This Zephyr config includes support for:

 * UART (present on he debug header of the board), tested with the
   hello_world sample application;
 * the one standalone LED (CAP_MIS), tested with the blinky sample
   application;
 * the rotary encoder (PDO_SEL), via ADC, tested with the adc sample
   application;
 * the current sense amplifier (I_SENSE), currently untested;
 * the SPI bus, connected internally in the UPD301C to the UPD350;
 * the I2C bus, exposed on the debug header, currently untested.

Note that the drivers.uart.async_api.rtt has to be disabled, as it is
for other m0 boards with no dma or it fails to build.

Signed-off-by: Diego Elio Pettenò <flameeyes@meta.com>