msm: mdss: Handle wfd READY event in display commit

Flicker is seen on wfd while rotation is done.
To prevent this, shared lock should be acquired properly
in case of READY event for wfd in display commit thread.

Change-Id: I0803eeb4d4f1d6283a6addaf40c435fded538718
Signed-off-by: Raghavendra Ambadas <rambad@codeaurora.org>