HardwareSerial - add changeBaudRate method (#2223)

* Add updateBaudRate to hardware serial

* remove flush

* Fix tab

cores/esp32/HardwareSerial.cpp

@@ -73,6 +73,11 @@ void HardwareSerial::begin(unsigned long baud, uint32_t config, int8_t rxPin, in
     }
 }
 
+void HardwareSerial::updateBaudRate(unsigned long baud)
+{
+	uartSetBaudRate(_uart, baud);
+}
+
 void HardwareSerial::end()
 {
     if(uartGetDebug() == _uart_nr) {

cores/esp32/HardwareSerial.h

@@ -57,6 +57,7 @@ public:
 
     void begin(unsigned long baud, uint32_t config=SERIAL_8N1, int8_t rxPin=-1, int8_t txPin=-1, bool invert=false, unsigned long timeout_ms = 20000UL);
     void end();
+    void updateBaudRate(unsigned long baud);
     int available(void);
     int availableForWrite(void);
     int peek(void);