Fix voice access problem on location page.

- Remove the seletcable attribute on footer preference so that
voice access can identify learn more.
- Apply latest footer preference API to set an action on learn more.
- Remove unuse string resource.

Test: Verify that talkback and voice access work well.
Fix: 189652942
Change-Id: I45fcd21d6a2d693d8b5eaa446aaccb769f1c0c7f