Fix to mute/unmute properly while adding a call

Call setMuteInternal instead of setMute while adding
call to an existing active call.

Change-Id: I9c9efa22d8b5d6ddf00ba19e866cdb153474f5c8
CRs-Fixed: 650135
InCallUI: 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: I7e829d3eefe246801021571e0028085204f1f499