media: platform: mtk-mdp3: avoid multiple driver registrations

media: platform: mtk-mdp3: avoid multiple driver registrations

The amount of MDP3 driver probes is determined by the registered
clocks of MMSYS.
Since MT8195 MDP3 utilizes VPPSYS0 and VPPSYS1, it's necessary to
prevent multiple driver registrations.

Signed-off-by: Moudy Ho <moudy.ho@mediatek.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Signed-off-by: Sebastian Fricke <sebastian.fricke@collabora.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>