drm: Retain reference to blob properties in lookup

When we look up a blob property, make sure we retain a reference to the
blob for the lifetime.

v2: Use DRM_MODE_PROP_BLOB, not PROP_OBJECT + OBJECT_BLOB.
Signed-off-by: Daniel Stone <daniels@collabora.com>
Tested-by: Sean Paul <seanpaul@chromium.org>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/drm_crtc.c

@@ -4775,7 +4775,8 @@ void drm_property_change_valid_put(struct drm_property *property,
 	if (drm_property_type_is(property, DRM_MODE_PROP_OBJECT)) {
 		if (property->values[0] == DRM_MODE_OBJECT_FB)
 			drm_framebuffer_unreference(obj_to_fb(ref));
-	}
+	} else if (drm_property_type_is(property, DRM_MODE_PROP_BLOB))
+		drm_property_unreference_blob(obj_to_blob(ref));
 }
 
 /**