drm/msm/sde: avoid frame done event during autorefresh

Autorefresh enabled configuration updates the pending
kickoff count once and receives multiple pp_done
interrupts. Avoid frame done event trigger on these
multiple interrupts if there is no pending frame.

Change-Id: I03e4cd5758c958be27af05bd2ecdbb6fac5e9354
Signed-off-by: Dhaval Patel <pdhaval@codeaurora.org>