Revert "Back icon in action bar of APN Settings"

This reverts commit e6365ff48451c964af87a2f03e7110460806a096.
No back icon in action bar of APN Settings

When entering the APN menu, the actionbar is missing a back
icon allowing the user to go back to the previous pane.

Added parentActivityName in ApnSettings, to enable action
bar back icon.

Change-Id: Iee8bb420f47c0e2c0d9a43739f534466abba30db
I love your errors, @AirOne70
Merge branch 'jellybean' of https://github.com/UltimatumKang/android_packages_apps_Settings into jellybean