drm/msm/dsi-staging: add support for dynamic mode switch

Provide support for seamless mode switching in supported panels.
Currently support is limited to smart panels. This changes modifies
drm bridge handlers to support seamless switch by reconfiguring the
DSI controllers with display timing values of the new mode.

Change-Id: Iece513077d76176ca7fa56a3e78c854bdb2b713a
Signed-off-by: Jeykumar Sankaran <jsanka@codeaurora.org>