media: mtk-mdp: handle vpu_wdt_reg_handler() errors during probe

This is a cleanup to better handle errors during MDP probe.

Signed-off-by: Eizan Miyamoto <eizan@chromium.org>
Reviewed-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>