panfrost: gen_pack: Fix gnu-empty-initializer errors

Fixes: 1b27817f1755 ("panfrost: gen_pack: Allow empty structs")
Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>
Tested-by: Vinson Lee <vlee@freedesktop.org>
Reviewed-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
Reviewed-by: Tomeu Vizoso <tomeu.vizoso@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/6811>
1 file changed