disp: msm: dsi: enable dfps trigger at mdp intf flush

This change allows dynamic refresh trigger to sw trigger
and mdp intf flush. With this we can make sure that DSI
timing/clock update and mdp intf timings are updated in
one vsync.

Change-Id: Ic807f498e2e47be6dd0f1e11ff1fc0896a8ec758
Signed-off-by: Vara Reddy <varar@codeaurora.org>