Fix wrong 'maximum_data_size' key in boards.txt

Author: cmaglie

hardware/arduino/avr/boards.txt

@@ -649,7 +649,7 @@ robotControl.name=Arduino Robot Control
 robotControl.upload.tool=avrdude
 robotControl.upload.protocol=avr109
 robotControl.upload.maximum_size=28672
-robotControl.upload.data_size=2560
+robotControl.upload.maximum_data_size=2560
 robotControl.upload.speed=57600
 robotControl.upload.disable_flushing=true
 robotControl.upload.use_1200bps_touch=true
@@ -679,7 +679,7 @@ robotMotor.name=Arduino Robot Motor
 robotMotor.upload.tool=avrdude
 robotMotor.upload.protocol=avr109
 robotMotor.upload.maximum_size=28672
-robotMotor.upload.data_size=2560
+robotMotor.upload.maximum_data_size=2560
 robotMotor.upload.speed=57600
 robotMotor.upload.disable_flushing=true
 robotMotor.upload.use_1200bps_touch=true