msm: mdss: adjust command mode bandwidth with hblank factor

Multiply a hblank factor (h_total/h_active) for command mode overlap
bandwidth vote. The current vote is little lower because transfer may
happen during horizontal blank period.

Change-Id: Id43459670ba9340c6027ea69df5a12fb07a4bf8b
Signed-off-by: Huaibin Yang <huaibiny@codeaurora.org>
Signed-off-by: Ingrid Gallardo <ingridg@codeaurora.org>