policy_hal: Fix to route the call to proper device

When voice/volte call is setup over USB headset, the call is
still on USB headset even after turning on speaker.

Don't set the device to USB headset when speaker is forced
by Telephony during call.

Change-Id: If6a95895a33423ff5150862a823fc669fd44e59a
CRs-Fixed: 588884