msm_fb: display:  add mdp bandwidth runtime calculation

Currently mdp bandwidth request logic is based on source image size
and number of layers. This logic can not support complicated mdp
usecases and it is not power efficient. The logic is improved by
calculating mdp bandwidth request at runtime from all pipes and mixers.

CRs-fixed: 425823
Change-Id: I63206f00f8d3017a2449f8ac617fce3ba2a4d36c
Signed-off-by: Huaibin Yang <huaibiny@codeaurora.org>