disp: msm: sde: skip power events when cont-splash is enabled

Skip reprogramming some HW blocks during power events to avoid
overwriting settings done by bootloader until we have completely
transitioned out from continuous splash.

Change-Id: I49a4834e22080dffc85f55bca9436bc894353335
Signed-off-by: Steve Cohen <cohens@codeaurora.org>