msm_fb: display: Add BLT support to dsi command mode panel

At run time, mdp BLT (writeback) mode is enabled and disabled
base on performance level to avoid mdp underrun. Move BLT
enabled/disabled logic to pan display so that enabled/disable
is done per commit instead of per queue. Since all panels
are shared same logic, dsi video mode and lcdc panel BLT logic
have been changed accordingly.

Change-Id: I6e04bf0f7bf1c13634e19b18d8ac4368affbc4d8
Signed-off-by: Kuogee Hsieh <khsieh@codeaurora.org>