TeleService: Update mute state accordingly after adding call

The mute state of sub1 that is stored in the mute table isn't restored to
the previous state when the second call(on sub2) is connected.

Restore the mute state for sub1 in CallButtonPresenter#refreshMuteState().

CRs-Fixed: 660470

Change-Id: Id9e0bf9c7e41ccb7cf210f8adfa0938ead650f74