drm: omapdrm: gem: Free the correct memory object

The GEM object free handler frees memory allocated by the driver using
the pointer to the drm_gem_object instead of the pointer to the
omap_gem_object that embeds it. This doesn't cause any issue in practice
as the drm_gem_object is the first field of omap_gem_object, but would
cause memory corruption if the structure layout changes. Fix it.
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>

drivers/gpu/drm/omapdrm/omap_gem.c

@@ -1345,7 +1345,7 @@ void omap_gem_free_object(struct drm_gem_object *obj)
 
 	drm_gem_object_release(obj);
 
-	kfree(obj);
+	kfree(omap_obj);
 }
 
 /* GEM buffer object constructor */