msm_fb: display: disable mdp blt mode

The switch of blt mode may cause mdp hang on some targets. To avoid
blt switch, we won't allocate the pipe that requires blt
mode. Basically this implies two things: downscaling is done by
rotator and gpu composition is used in case of blt mode is needed.

This implementation is to calculate mdp clk requirement based on the
req data passed from userspace before setting the actural pipe
data. If overlay_set asks for mdp clk that is greater than
mdp_max_clk, meaning blt is needed, overlay_set returns before pipe
allocation or pipe data change, so this way can avoid mdp to work on
wrong pipe data.

Change-Id: I22e73d08bed920b366c18ee21b132339cf2a0347
Signed-off-by: Huaibin Yang <huaibiny@codeaurora.org>