apu: fix deadlock on _apu_bo_del

_apu_bo_del tries to get the lock on table_lock but it can be called from free_apu_cached_bo which is already inside the lock from apu_device_del leading to a deadlock.

removing the lock mechanism inside _apu_bo_del and add it before calling it

Signed-off-by: Julien Stephan jstephan@baylibre.com