Bluetooth: Don't set a null alias before unpairing

* This causes the unpair action to throw a null pointer exception and
  bring down the Settings app. Don't do this.

Change-Id: I0c60437f5ea934385a037a464743e24c9d341aca
Merge "Bluetooth: Don't set a null alias before unpairing" into cm-11.0
Merge branch 'cm-11.0' of git://github.com/CyanogenMod/android_packages_apps_Settings into cd-4.4