Rollback @SystemApi on ApnSetting

* Remove @SystemApi from ApnSetting.TYPE_*
* Remove @SystemApi from ApnSetting.getApnTypesStringFromBitmask

Bug: 147465477
Bug: 151245732
Test: make \ flash
Merged-In: Ifc781ae494968fbaad8c591dbd990d397e0d733b
Change-Id: Ifc781ae494968fbaad8c591dbd990d397e0d733b
2 files changed