msm: mdss: refactor performance calculations

Current logic could potentially lead to drop in performance (and
underflow) when multiple panels are there and both are updating mixer
configuration independently, as we may end up raising bus bandwidth for
another panel which may not be ready just yet. This is addressed by
updating performance configuration values until it's ready to switch
rather than updating values and performing these later (other panel
update could come in between).

Change-Id: I247ef0cd3e0616de3e5ddd9599233af570e422a5
Signed-off-by: Adrian Salido-Moreno <adrianm@codeaurora.org>
Signed-off-by: Huaibin Yang <huaibiny@codeaurora.org>