bugfix - serial config parameter cannot be set

function usart_init must be called before usart_config_gpios_async

Author: stevstrong

STM32F1/cores/maple/HardwareSerial.cpp

@@ -141,11 +141,11 @@ void HardwareSerial::begin(uint32 baud, uint8_t config)
 
     disable_timer_if_necessary(txi->timer_device, txi->timer_channel);
 
+    usart_init(this->usart_device);
     usart_config_gpios_async(this->usart_device,
                              rxi->gpio_device, rxi->gpio_bit,
                              txi->gpio_device, txi->gpio_bit,
                              config);
-    usart_init(this->usart_device);
     usart_set_baud_rate(this->usart_device, USART_USE_PCLK, baud);
     usart_enable(this->usart_device);
 }