boards: mec1501modular_assy6885: Add support for UART0
boards: mec1501modular_assy6885: Add support for UART0

Add options to configure UART0 and pins based upon device
tree settings.

Signed-off-by: Scott Worley <186210b307f58d6c0a191337b635ed93ad075837@microchip.com>

finikorg/zephyr,finikorg/zephyr,Vudentz/zephyr,Vudentz/zephyr,galak/zephyr,galak/zephyr,zephyrproject-rtos/zephyr,nashif/zephyr,finikorg/zephyr,zephyrproject-rtos/zephyr,zephyrproject-rtos/zephyr,Vudentz/zephyr,galak/zephyr,finikorg/zephyr,nashif/zephyr,zephyrproject-rtos/zephyr,zephyrproject-rtos/zephyr,nashif/zephyr,galak/zephyr,finikorg/zephyr,Vudentz/zephyr,nashif/zephyr,Vudentz/zephyr,galak/zephyr,Vudentz/zephyr,nashif/zephyr