Autofill binding permission fixes.

- Removed deprecated BIND_AUTO_FILL
- Renamed BIND_AUTOFILL to BIND_AUTOFILL_SERVICE
- Kept BIND_AUTOFILL as @hide
- Fixed the permission code

The permission check was actually ignored; it was probably broken when we
introduced support to settings.

Fixes: 37723410
Bug: 37563972
Test: manual verification with existing client
Test: CtsAutoFillServiceTestCases pass

Change-Id: If3abdcb0ae850f0a327bfdbb9ca6c44a24823047