pcm: extplug: refinement of masks in extplug
pcm: extplug: refinement of masks in extplug

It should be possible to use empty mask format with extplug.
The refinement of mask via extplug is now modified,
to accept empty masks as well to work properly.

Signed-off-by: Awais Belal <baf2432feba4880e6c7e4eae0da0831b9a17e752@mentor.com>
Signed-off-by: Mounesh Sutar <ac1512b6c2fa49c8282587b084eecb53c9318ce5@gmail.com>
Signed-off-by: Takashi Iwai <4596b3305151c7ee743192a95d394341e3d3b644@suse.de>

tiwai/alsa-lib,takaswie/alsa-lib,tiwai/alsa-lib,takaswie/alsa-lib,takaswie/alsa-lib,alsa-project/alsa-lib,alsa-project/alsa-lib,tiwai/alsa-lib,takaswie/alsa-lib,alsa-project/alsa-lib,takaswie/alsa-lib,alsa-project/alsa-lib,tiwai/alsa-lib