msm: mdss: add fudge factor to single pipe scenarios

Add fudge factor to ib vote for scenarios with high
bandwidth request whenever a single pipe is present,
this is to account for inefficiencies as recommended.

Change-Id: I6bdfb8d71c61f58a26fae95bdbd5bc9a2d043957
Signed-off-by: Ingrid Gallardo <ingridg@codeaurora.org>