Arduino Due fixes for shield compatibility
Arduino Due fixes for shield compatibility

tchangw/Adafruit_NFCShield_I2C,adafruit/Adafruit_NFCShield_I2C,shangdawei/Adafruit_NFCShield_I2C,tchangw/Adafruit_NFCShield_I2C,adafruit/Adafruit_NFCShield_I2C