media: drm/mediatek: Get rid of mtk_smi_larb_get/put

MediaTek IOMMU has already added the device_link between the consumer
and smi-larb device. If the drm device calls the pm_runtime_get_sync,
the smi-larb's pm_runtime_get_sync also be called automatically.

CC: CK Hu <ck.hu@mediatek.com>
CC: Philipp Zabel <p.zabel@pengutronix.de>
Signed-off-by: Yong Wu <yong.wu@mediatek.com>
Reviewed-by: Evan Green <evgreen@chromium.org>
Acked-by: Chun-Kuang Hu <chunkuang.hu@kernel.org>
Reviewed-by: Dafna Hirschfeld <dafna.hirschfeld@collabora.com>
Tested-by: Frank Wunderlich <frank-w@public-files.de> # BPI-R2/MT7623
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>