Fix VibrationSettings to handle missing AudioManager

Update VibrationSettings to handle devices that do not provide
AudioManager service.

Fix: 380022127
Flag: EXEMPT small bugfix
Test: VibrationSettingsTest
Change-Id: I5db3f6b99224c335109e83312fd6bc6252d23392
Merged-In: I5db3f6b99224c335109e83312fd6bc6252d23392
(cherry picked from commit e61fd3810b0594c5b0ffe11c0beb4f94921b601e)
2 files changed