Reverting a change introduced in 6de7e7f8b3698 "[drm] upstream sync to v4.10"
(upstream c470abd4fde40ea).

Index: src/drivers/gpu/drm/mgag200/mgag200_drv.c
===================================================================
--- src.orig/drivers/gpu/drm/mgag200/mgag200_drv.c	2017-06-20 20:40:49.310698789 +0200
+++ src/drivers/gpu/drm/mgag200/mgag200_drv.c	2017-06-20 20:40:51.234670270 +0200
@@ -103,7 +103,7 @@
 	.minor = DRIVER_MINOR,
 	.patchlevel = DRIVER_PATCHLEVEL,
 
-	.gem_free_object_unlocked = mgag200_gem_free_object,
+	.gem_free_object = mgag200_gem_free_object,
 	.dumb_create = mgag200_dumb_create,
 	.dumb_map_offset = mgag200_dumb_mmap_offset,
 	.dumb_destroy = drm_gem_dumb_destroy,