intel: Add handle to hashtable before freeing along an error path

drm_intel_gem_bo_free() unconditionally attempts to remove the handle
from the hashtable. This goes horribly wrong if we haven't already added
the bo to the hashtable.

Reported-by: Michael Thayer <michael.thayer@oracle.com>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>