disp: msm: dsi: commit DSI PHY timings after update

DSI PHY timings must be committed every time the values
are updated after a dynamic mode switch.

Change-Id: Id605c76dfe75ec41ceb89000f24baccda189e82f
Signed-off-by: Satya Rama Aditya Pinapala <psraditya30@codeaurora.org>