msm: mdss: Avoid setting esd_rdy to false in panel off

When the phone is in suspend mode, the panel turns ON and
OFF whenever it receives the message for ambient display.
There are cases whenever the Power Key is pressed, it skips
the Panel ON because already the state of the Panel is ON
and the esd_rdy didn't turn to true, which was set to false
during Panel OFF event. This result in ESD being disabled
sometimes when we coming out of ambient mode. Hence set
esd_rdy to true once during bootup and never set this back
to false.

Change-Id: I0cb4d7f02e0018125b6886651be99e93551f3301
Signed-off-by: Jayant Shekhar <jshekhar@codeaurora.org>
Signed-off-by: sbhayare <sachin.bhayare@codeaurora.org>