drm/i915: unpin for an invalid memory domain.

A missing unreference and unpin after rejecting the relocation for an
invalid memory domain.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NEric Anholt <eric@anholt.net>
Signed-off-by: NDave Airlie <airlied@linux.ie>

drivers/gpu/drm/i915/i915_gem.c

@@ -2254,6 +2254,8 @@ i915_gem_object_pin_and_relocate(struct drm_gem_object *obj,
 				  (int) reloc.offset,
 				  reloc.read_domains,
 				  reloc.write_domain);
+			drm_gem_object_unreference(target_obj);
+			i915_gem_object_unpin(obj);
 			return -EINVAL;
 		}