Settings: Fix force close for telephony callback exceeding limitation

When sub info changed, new telephony callback will be registered but old telephony callback not un-registered. Finally result in force close for registered telephony callback count exceeding its allowed.

No need to re-registered the telephony callback for one sub if registered.

Bug: 328716180

Change-Id: Ia0c3b311b5b5cc77f061d81ec21250abde2fa9f4