[media] media: mtk-mdp: NULL-terminate mtk_mdp_comp_dt_ids

The mtk_mdp_comp_dt_ids[] array should be NULL-terminated; add therefore an
empty entry in the end.

Fixes: c8eb2d7e ("[media] media: Add Mediatek MDP Driver")

Signed-off-by: Vincent Stehlé <vincent.stehle@laposte.net>
Cc: Minghsiu Tsai <minghsiu.tsai@mediatek.com>
Cc: Mauro Carvalho Chehab <mchehab@s-opensource.com>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>