msm: mdss: Avoid unclocked register access with dsi_event_thread

In the case when ESD status check fails with DSI ACK
errors, there is a chance of unclocked register access when
DSI_INTR_CTRL register is being set.

Change-Id: I629b4ec642a86369b6ed693bdc6f8b4260ec1f5d
Signed-off-by: Vineet Bajaj <vbajaj@codeaurora.org>