msm: mdss: Adding lcd notifier

Supports notifier for start&end of LCD power on&off

Change-Id: Idaa685a2c554286da5f764519305d830c4d1a1bd
Signed-off-by: Se Hun Kim <sean2.kim@lge.com>
Signed-off-by: Jongrak Kwon <jongrak.kwon@lge.com>
Signed-off-by: Devin Kim <dojip.kim@lge.com>