drm/mediatek: separate mipi_tx to different file

Different IC has different mipi_tx setting of dsi.
This patch separates the mipi_tx hardware relate part for mt8173.

Signed-off-by: Jitao Shi <jitao.shi@mediatek.com>
Signed-off-by: CK Hu <ck.hu@mediatek.com>
4 files changed