drm/msm/dsi: Add support for msm8x94

DSI controller on msm8x94 is version 1.3, which requires different
power supplies and works with 20nm DSI PHY. This change is to add
the basic support for this version.

Signed-off-by: Hai Li <hali@codeaurora.org>
Signed-off-by: Rob Clark <robdclark@gmail.com>