drm/msm/sde: fix deadlock between ESD check and power mode update

In the current implementation there can be a scenario in which
one thread i.e. power mode update, is waiting for ESD check work
to finish by holding connector lock and at the same time in
another thread ESD work itself is waiting on connector lock to
be released. Fix this deadlock situation by releasing the connector
lock before waiting for ESD check to finish.

Change-Id: I722b8f7805c8ed3bb9328c34232dabcd97455e00
Signed-off-by: Sandeep Panda <spanda@codeaurora.org>