drm/msm/dsi: Add new method to calculate 14nm PHY timings

The 14nm DSI PHY on 8x96 (called PHY v2 downstream) requires a different
set of calculations for computing D-PHY timing params. Create a
timing_calc_v2 func for the newer v2 PHYs.

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