sdm: provide CONTROL_BACKLIGHT support

Implement CONTROL_BACKLIGHT binder support.
This binder supports ability to control screen updates and
backlight brightness.
Usage:
To turn off backlight on primary
adb shell "service call display.qservice 20 i32 0"

To restore backlight on primary
adb shell "service call display.qservice 20 i32 1"

Change-Id: I5ec9277d606dcbf31f316d6f7e0c93a27806910d
4 files changed