Support Arduino MEGA boards for RFM69 interrupt config

Author: fallberg

libraries/MySensors/utility/RFM69.h

@@ -40,7 +40,7 @@
 #if defined(__AVR_ATmega168__) || defined(__AVR_ATmega328P__) || defined(__AVR_ATmega88) || defined(__AVR_ATmega8__) || defined(__AVR_ATmega88__) || defined(__AVR_ATmega32U4__)
   #define RF69_IRQ_PIN          2
   #define RF69_IRQ_NUM          0
-#elif defined(__AVR_ATmega644P__) || defined(__AVR_ATmega1284P__)
+#elif defined(__AVR_ATmega644P__) || defined(__AVR_ATmega1284P__) || defined(__AVR_ATmega2560__)
   #define RF69_IRQ_PIN          2
   #define RF69_IRQ_NUM          2
 #endif