Configure_USART() function

None

This function is used to : -1- Enable GPIO clock and configures the USART2 pins. -2- Enable the USART2 peripheral clock and clock source. -3- Configure USART2 functional parameters. -4- Enable USART2. Peripheral configuration is minimal configuration from reset values. Thus, some useless LL unitary functions calls below are provided as commented examples - setting is default configuration from reset.