Update the MD5 of the firmware for Raspberry Pi to enable build on the Chaos Calmer / 15.05.1 target again.
The checksum changed due to changes of the Github Tar Handling as described here: raspberrypi/firmware#873
After that change, builds for RPi on 15.05.1 succeed again. Signed-off-by: Nico Maas <mail@nico-maas.de>