Allow blank_screen to make binder calls to the servicemanager

blank_screen can not find and use the lights HAL if it cannot use the servicemanager. This
broke turning off the display during shutdown.

Change-Id: I6aff1cb71f805637abc79493ba2574143c5cf7cf
Test: adb root; adb shell setenforce 1; adb shell setprop ctl.start blank_screen
Test: adb logcat -b all | grep 'denied'
Bug: 151363454
2 files changed