drm/mtk: Drop drm_gem_prime_export/import

They're the default.

Aside: Would be really nice to switch the others over to
drm_gem_object_funcs.
Reviewed-by: Eric Anholt <eric@anholt.net>
Reviewed-by: Emil Velikov <emil.velikov@collabora.com>
Reviewed-by: CK Hu <ck.hu@mediatek.com>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Cc: CK Hu <ck.hu@mediatek.com>
Cc: Philipp Zabel <p.zabel@pengutronix.de>
Cc: Matthias Brugger <matthias.bgg@gmail.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-mediatek@lists.infradead.org
Link: https://patchwork.freedesktop.org/patch/msgid/20190614203615.12639-20-daniel.vetter@ffwll.ch

drivers/gpu/drm/mediatek/mtk_drm_drv.c

@@ -329,8 +329,6 @@ static struct drm_driver mtk_drm_driver = {
 
 	.prime_handle_to_fd = drm_gem_prime_handle_to_fd,
 	.prime_fd_to_handle = drm_gem_prime_fd_to_handle,
-	.gem_prime_export = drm_gem_prime_export,
-	.gem_prime_import = drm_gem_prime_import,
 	.gem_prime_get_sg_table = mtk_gem_prime_get_sg_table,
 	.gem_prime_import_sg_table = mtk_gem_prime_import_sg_table,
 	.gem_prime_mmap = mtk_drm_gem_mmap_buf,