ao_pulse: drop video role; fixes random muting

The details are described in #1173.

This "features" causes problems to users so often, it's better to remove
it.

Fixes #1173.

audio/out/ao_pulse.c

@@ -419,7 +419,6 @@ static int init(struct ao *ao)
         MP_ERR(ao, "Failed to allocate proplist\n");
         goto unlock_and_fail;
     }
-    (void)pa_proplist_sets(proplist, PA_PROP_MEDIA_ROLE, "video");
     (void)pa_proplist_sets(proplist, PA_PROP_MEDIA_ICON_NAME, ao->client_name);
 
     pa_format_info_set_rate(format, ao->samplerate);