am33x-cm3: remove

am33x-cm3: remove

This is currently unused and not working anyway, since the used upstream
kernel loads am335x-pm-firmware.elf and not am335x-pm-firmware.bin [0].

The last downstream patches using the latter were removed with e4eef7e6.

Remove it instead of fixing it since the rtc-only sleep state can even
damage the hardware [1].

[0] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=ccbbb9faac946ce61c241ce9f08b3486fabf031d
[1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=7a6cb0abe1aa63334f3ded6d2b6c8eca80e72302

Signed-off-by: Andre Heider <a.heider@gmail.com>