Fix Arduino.h portOutputRegister() and portModeRegister()

This functions were using the OUTSET and DIRSET registers instead
of SET and DIR. The xxxSET registers only do something when a "1"
is written to any of their bits, writting a "0" does nothing.

cores/nRF5/Arduino.h

@@ -109,9 +109,9 @@ void loop( void ) ;
 #error "Unsupported GPIO_COUNT"
 #endif
 
-#define portOutputRegister(port)   ( &(port->OUTSET) )
+#define portOutputRegister(port)   ( &(port->OUT) )
 #define portInputRegister(port)    ( &(port->IN) )
-#define portModeRegister(port)     ( &(port->DIRSET) )
+#define portModeRegister(port)     ( &(port->DIR) )
 #define digitalPinHasPWM(P)        ( true )
 
 /*