disp: msm: remove unnecessary vblank get and put

Remove unnecessary vblank get and put. This call is
not required before calling wait for crtc commit done
because downstream driver has its own vblank refcount.
Without this change vblank enable call is seen every
vsync.

Change-Id: I1c692f1d2084dbe7ad2f594ddae3907a4a10bb96
Signed-off-by: Samantha Tran <samtran@codeaurora.org>