disp: msm: sde: add refresh rate to msm_drm_notifier

Include the current vrefresh in the msm_drm_notifier data provided to
registered clients.

Change-Id: I9b8a994a31baca1158972c17753000f3c27020b7
(cherry picked from commit 6366ce4696fb4047cd5db029670851f9407966a8)
Signed-off-by: Steve Pfetsch <spfetsch@google.com>
[samtran@codeaurora.org: resolve trivial merge conflicts]
Signed-off-by: Samantha Tran <samtran@codeaurora.org>
Signed-off-by: Dhaval Patel <pdhaval@codeaurora.org>