drm/sun4i: Use .dumb_map_offset and .dumb_destroy defaults

This driver can use the drm_driver.dumb_destroy and
drm_driver.dumb_map_offset defaults, so no need to set them.

Cc: Maxime Ripard <maxime.ripard@free-electrons.com>
Signed-off-by: Noralf Trønnes <noralf@tronnes.org>
Acked-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Link: https://patchwork.freedesktop.org/patch/msgid/1500837417-40580-18-git-send-email-noralf@tronnes.org

drivers/gpu/drm/sun4i/sun4i_drv.c

@@ -40,8 +40,6 @@ static struct drm_driver sun4i_drv_driver = {
 
 	/* GEM Operations */
 	.dumb_create		= drm_gem_cma_dumb_create,
-	.dumb_destroy		= drm_gem_dumb_destroy,
-	.dumb_map_offset	= drm_gem_cma_dumb_map_offset,
 	.gem_free_object_unlocked = drm_gem_cma_free_object,
 	.gem_vm_ops		= &drm_gem_cma_vm_ops,