Fixing Serialx pins mismatch

Signed-off-by: Thibaut VIARD <[email protected]>

Author: aethaniel

variants/arduino_zero/variant.cpp

@@ -207,5 +207,5 @@ SERCOM sercom3( SERCOM3 ) ;
 SERCOM sercom4( SERCOM4 ) ;
 SERCOM sercom5( SERCOM5 ) ;
 
-Uart Serial1( &sercom0, PIN_SERIAL_RX, PIN_SERIAL_TX ) ;
+Uart Serial1( &sercom0, PIN_SERIAL1_RX, PIN_SERIAL1_TX ) ;
 Uart Serial( &sercom5, PIN_SERIAL_RX, PIN_SERIAL_TX ) ;