* Removed assert if RAIL_StartTx() fails. It will report the error and continue
* Updated Makefile.am to fix missing header and prettified radio.c
* Added OPENTHREAD_CONFIG_NCP_UART_ENABLE to efr32mg12 config
* renamed efr32 in two for mg12 and mg21 and radio changes for mg12
Change to radio interface code, check the txBusy flag before
attempting to transmit a packet Cleaner auto state transition code and
safer event handling Use HAL_PA_VOLTAGE in all hal-config.h files
* uart flow control mode is configured from board /hal-config.h
Allows a different flow control mode for each EFR32 board as
necessary. (hw flow control is not presently implemented on
Thunderboard Sense so HAL_USART_FLOW_CONTROL_NONE mode should be used
for BRD4166A, other boards use HAL_USART_FLOW_CONTROL_HWUART)