Update platform define, removing SAM3X* and replacing with __SIM3U1XX__.
Update platform define, removing SAM3X* and replacing with __SIM3U1XX__.

boltonja/armduino,boltonja/armduino,boltonja/armduino,boltonja/armduino,boltonja/armduino,boltonja/armduino,boltonja/armduino