msm: mdss: remove display commit during overlay play

All display commits happen with pan display in order to have a single
sync point when using multiple pipes, and avoid blinks that can happen
when updating surfaces out of sync.

Exception for this case is writeback where commit is still needed, keep
this implementation until this exception is corrected from user space
applications.

CRs-Fixed: 408105
Change-Id: Ib40c4872f43e6a939c45624677b2ab1f64a3b31e
Signed-off-by: Adrian Salido-Moreno <adrianm@codeaurora.org>