msm: mdss: Disable ESD thread during display shutdown

During device power off, in display shutdown sequence, the
FB event notifier for poweroff doesn't get called. In this
case, disable the ESD thread before turning panel off to avoid
a race condition between ESD and shutdown flow.

Change-Id: I33a326eb1e34f24447fb193ec060c3a70d8a6954
Signed-off-by: Nirmal Abraham <nabrah@codeaurora.org>