drm/amdkfd: Don't BUG on freeing GART sub-allocation

Instead of creating a BUG if trying to free a NULL GART sub-allocation object,
just return 0 (success).

This is done to mirror behavior of kfree.

Signed-off-by: Oded Gabbay <oded.gabbay@amd.com>
This commit is contained in:
Oded Gabbay 2015-01-12 22:34:21 +02:00
commit 9216ed2940