RUI UART Initialize

RUI_RETURN_STATUS rui_uart_init(RUI_UART_DEF uart_def,RUI_UART_BAUDRATE baudrate);

@brief	This API is used to configure the parameters for UART.
@return	RUI_RETURN_STATUS
@param	RUI_UART_DEF uart_def:the instance of UART. RUI_UART_BAUDRATE baudrate: UART baudrate value
@module	RAK811, RAK4200, RAK4400, RAK4600, and RAK5010.