drm/shmobile: 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: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Noralf Trønnes <noralf@tronnes.org>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Link: https://patchwork.freedesktop.org/patch/msgid/1500837417-40580-15-git-send-email-noralf@tronnes.org

drivers/gpu/drm/shmobile/shmob_drm_drv.c

@@ -145,8 +145,6 @@ static struct drm_driver shmob_drm_driver = {
 	.gem_prime_vunmap	= drm_gem_cma_prime_vunmap,
 	.gem_prime_mmap		= drm_gem_cma_prime_mmap,
 	.dumb_create		= drm_gem_cma_dumb_create,
-	.dumb_map_offset	= drm_gem_cma_dumb_map_offset,
-	.dumb_destroy		= drm_gem_dumb_destroy,
 	.fops			= &shmob_drm_fops,
 	.name			= "shmob-drm",
 	.desc			= "Renesas SH Mobile DRM",