status bar power menu: be sure to update visibility when showing qs details

fix status bar power menu icon showing up if previously disabled
step to reproduce:
- enable status bar power menu
- disable it
- pull down qs and tap data icon
- close data details
- status bar power menu icon will be visible even if disabled

thanks @enricocid for the bug report

Conflicts:
	packages/SystemUI/src/com/android/systemui/statusbar/phone/StatusBarHeaderView.java