Fix crash in developer settings when backup is not available

When backup feature is disabled, Developer Settings dialog does
not come up due to a crash.

Disable Backup Password option in the preference screen.

Bug: 64725174
Test: Developer settings dialog comes up and Backup password is
      disabled on Polaris

Change-Id: I4f4546c4e97d2e5128ec65c0532691d9799b4c8f