firmware/am335x-pm-firmware.bin: copied in power management firmware

Binary URL: https://github.com/beagleboard/am33x-cm3/blob/master/bin/am335x-pm-firmware.bin?raw=true
Source: http://github.com/beagleboard/am33x-cm
Commit: f4163300590ae782cdbf9a764dc2456924114c91