drm/mediatek: Power on/off devices with function pointers

drm/mediatek: Power on/off devices with function pointers

Different from OVL, OVL adaptor is a pseudo device so we didn't
define it in the device tree, consequently, pm_runtime_resume_and_get()
called by .atomic_enable() powers on no device. For this reason, we
implement a function to power on the RDMAs in OVL adaptor, and the
system will make sure the IOMMUs are powered on as well because of the
device link (iommus) in the RDMA nodes in DTS.

This patch separates power and clock management process, it would be
easier to maintain and add extensions.

Reviewed-by: CK Hu <ck.hu@mediatek.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Signed-off-by: Hsiao Chien Sung <shawn.sung@mediatek.com>
Link: https://patchwork.kernel.org/project/dri-devel/patch/20231214055847.4936-15-shawn.sung@mediatek.com/
Signed-off-by: Chun-Kuang Hu <chunkuang.hu@kernel.org>