audio: Handle sonification for last stream in stopOutput

-Low visibility stream is not muted during voice call when
played back to back.
-In startOutput, handleInCallSonification is called only for
first time i.e. mRefCount is 1. While in stopOutput, it is
called without any check on refCount.
So the second notification stream gets played when stopOutput
of first stream unmutes the muted stream.
-Handle sonification while in call only for last stream in
stopOutput i.e. mRefCount is 0.

CRs-Fixed: 645543
Change-Id: I73727c3cc39e7ceecfbc961c3accb109cd013d96
 Audio: Fix for audio loss on switching between speaker and USB headset

 - snd device reference count is not decremented when usb headset is
   unplugged, because touch tone is still active on usb headset.
   So when usb is plugged again device routing is not triggered as
   present and prev devices are same
 - Fix is to route audio to speaker as soon as usb headset is
   disconnected

   CRs-Fixed: 630425

Change-Id: Id07bc44a39f72f33b39fd180efd1859de63650e5
Merge " Audio: Fix for audio loss on switching between speaker and USB headset"
Merge "audio: Handle sonification for last stream in stopOutput"
wlan: Fix for improper comparison of driver_status string

This commit ensures driver load failure status is compared with
valid string which has the failure/success information.

Change-Id: I3b619ad0c005fb793d127bd2a23b376ed961d0b7
CRs-Fixed: 652539
Merge "wlan: Fix for improper comparison of driver_status string"