MT#61856 call_interfaces: play dtmf, use audio sink only

When iterating through the monologues medias while
looking for the media sink, filter those, which aren't audio.

Such a media type will likely have no audio subscriber,
and most probably will return with:
"There is no sink media capable of DTMF playback"

Change-Id: I86e64105e520f2a6f3ee9bbb0271830ae8d8cc69

daemon/call_interfaces.c

@@ -2056,6 +2056,8 @@ found:
 			struct call_media *ml_media = monologue->medias->pdata[i];
 			if (!ml_media)
 				continue;
+			if (ml_media->type_id != MT_AUDIO)
+				continue;
 
 			struct call_media * ms_media_sink = NULL;