msm: mdss: Allow resource update during secure UI

Add support for allowing backlight update during
secure UI eventhough the panel is in off state
and keep the panel regulator in on state.

Change-Id: I1e6d97742e2eb36f926b6fe765c13b9c5fd44b74
Signed-off-by: Krishna Manikandan <mkrishn@codeaurora.org>
Signed-off-by: Nirmal Abraham <nabrah@codeaurora.org>