TeleService: Null out the dialog when dismissed

Change-Id: I410de20ca21ca6947bef791fb958b4d21b2e4004
Automatic translation import

Change-Id: I960f4a950f08119d8732f38c9215eaea1fd7938e
Merge branch 'cm-11.0' of https://github.com/CyanogenMod/android_packages_services_Telephony into cm-11.0