media: mtk-mdp: Fix a reference leak bug in mtk_mdp_remove()

media: mtk-mdp: Fix a reference leak bug in mtk_mdp_remove()

In mtk_mdp_probe(), vpu_get_plat_device() increases the reference
count of the returned platform device. Add platform_device_put()
to prevent reference leak.

Fixes: c8eb2d7e8202 ("[media] media: Add Mediatek MDP Driver")
Cc: stable@vger.kernel.org
Signed-off-by: Haoxiang Li <haoxiang_li2024@163.com>
Signed-off-by: Nicolas Dufresne <nicolas.dufresne@collabora.com>
Signed-off-by: Hans Verkuil <hverkuil+cisco@kernel.org>