msm: mdss: dsi: return true when esd status is not enabled

Panel status check returns the current state based
on esd status check method. If esd method is not configured
then it returns panel dead which is misleading. This change
returns panel status alive if esd method is not enabled or
esd check callback is not registered for certain method.

Change-Id: I5df21df16618cd62b5d1495982ff889ed53ce31b
Signed-off-by: Dhaval Patel <pdhaval@codeaurora.org>