ignore telephony call state if telephony mgr state is idle

When re-connecting a BT headset, the headset state machine requests
telephony stack call state (through queryPhoneState) once
SLC is established. The answer is received asynchronously.

If there is a virtual call (e.g. voip/hang out/skype) ongoing while
connecting BT headset, the audio will be switched automatically to BT SCO
path once connected.

Issue: if the call state from telephony is received while the BT headset
is being used for a virtual call, then the virtual call is stopped,
even if there is no call ongoing, and audio will be routed back to primary
device (speaker/headset).

Proposal: ignore the telephony state in case there is a virtual
call ongoing, but no CSV call, and keep audio routed to the BT
SCO path.

Change-Id: If0ebe8c5cd08f48dd56a593e37f3f05a4fccfc97
jean-marie.bellouard <jean-marie.bellouard@intel.com>