Lockscreen Options : Disable keyguard camera only

Current method of disabling camera does so for entire system, not just
lockscreen. This patchset addresses that.

Change-Id: Iba357214df36ddd8afd49a3e39abcaaba4ec808e
Remove unused string.

Change-Id: I42efede12c7a8e501dcef5e6eed84839ec586716
Merge "Lockscreen Options : Disable keyguard camera only" into cm-10.1