BT: Avoid opening SCO for Alert->Active call state change

This patch avoids SCO opened for call state change from
alerting to active, which causes SCO to be established
even when we selected earpiece from Phone App UI.

Change-Id: Ic6a4f98a205782fd8528c35901e083cfa3b2fac7
CRs-Fixed: 488462
Merge "BT: Avoid opening SCO for Alert->Active call state change"
Merge remote-tracking branch 'caf/jb_2.5' into cm-10.1