drm/msm/dsi-staging: update dsi clock calculations

Change updates dsi clock calculations for command mode
as per recommendation. Now dsi clocks are tied to
frame transer time. Propagate correct frame transfer
time to hal to update mdp clocks and bandwidth needed
accordingly.

Change-Id: I46f9038622ddd47cc53c5f3d54229f69a7008c8a
Signed-off-by: Vara Reddy <varar@codeaurora.org>