[2/2] Settings: Hide power menu on lockscreen

Base: https://gerrit.omnirom.org/#/c/4700/

Change-Id: Ic485195060c071f120022a52cfd85226b0c3a414
Conflicts:
	res/values/mahdi_strings.xml
	res/xml/power_menu_settings.xml

Conflicts:
	res/xml/power_menu_settings.xml