disp: msm: sde: support qsync and vrr in same commit

This change adds support to program both qsync and variable
refresh rate in the same atomic commit. During dfps
usecase, if qsync is enabled, avr ctrl gets programmed
during prepare phase as well as after configuring timing
engine. This change also handles such scenarios to prevent
double programming of avr ctrl.

Change-Id: Ia1a7ff135a8a70aca11836fc39ca349ff6d743d2
Signed-off-by: Raviteja Tamatam <travitej@codeaurora.org>