msm: mdss: fix deadlock between display and dsi status check thread

The vsync handler in display thread holds ov_lock followed by
offlock. And the DSI status check thread for cmd mode panel holds
offlock followed by ovlock, causing a clear deadlock scenario.
Fix it by acquiring ov_lock before offlock in DSI status check
thread.

Change-Id: I54ef54b5ca7e4c87e909c510b28ff7770bb20a3b
Signed-off-by: Veera Sundaram Sankaran <veeras@codeaurora.org>