clk: mediatek: Add MT8188 imgsys clock support

Add MT8188 imgsys clock controllers which provide clock gate
control for image IP blocks.

Signed-off-by: Garmin.Chang <Garmin.Chang@mediatek.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Link: https://lore.kernel.org/r/20230331123621.16167-9-Garmin.Chang@mediatek.com


Signed-off-by: Stephen Boyd <sboyd@kernel.org>