drm/mediatek: dsi: Add mode_valid callback to DSI bridge

Support IGT (Intel GPU Tools) in Mediatek DSI driver.
According to the description of MIPI Alliance Specification for D-PHY
Version 1.1, the maximum supported data rate is 1.5Gbps, so add mode_valid
callback to dsi bridge to filter out the data rate exceeding the
Specification.

Signed-off-by: Shuijing Li <shuijing.li@mediatek.com>
Reviewed-by: CK Hu <ck.hu@mediatek.com>
Link: https://patchwork.kernel.org/project/dri-devel/patch/20230823092047.32258-1-shuijing.li@mediatek.com/


Signed-off-by: Chun-Kuang Hu <chunkuang.hu@kernel.org>