msm: mdss: Finetune ab votes for PPP

Current ab calculation pushed the power numbers very high.
Finentune the calculation and keep ib undisturbed.

Change-Id: Iddfa39a735201a52daae7278f4006fa6f929b19c
Signed-off-by: Shivaraj Shetty <shivaraj@codeaurora.org>
Signed-off-by: Sravan Kumar D.V.N <sravank1@codeaurora.org>