msm: display: change mdp default ib_factor to 150

system profiling found that mdp downscaling needs larger bandwidth
that is related to mdp ab request, so adding scaling factor to mdp ab
calculation reduces the chance of underruns.

ab - scaling factors - port0 and port1 split
ib - 1.5 x ab - no split and same on both ports

This is board file change for ib = 1.5 x ab

Change-Id: Ic267c6eb1a92e974e5f94f1a72b95433c73b11ae
Signed-off-by: Huaibin Yang <huaibiny@codeaurora.org>