ALSA: usb-audio: Filter error from connector kctl ops, too

The ignore_ctl_error option should filter the error at kctl accesses,
but there was an overlook: mixer_ctl_connector_get() returns an error
from the request.

This patch covers the forgotten code path and apply filter_error()
properly.  The locking error is still returned since this is a fatal
error that has to be reported even with ignore_ctl_error option.

BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=206873
Cc: <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20200412081331.4742-2-tiwai@suse.deSigned-off-by: Takashi Iwai <tiwai@suse.de>

sound/usb/mixer.c

@@ -1457,7 +1457,7 @@ static int mixer_ctl_connector_get(struct snd_kcontrol *kcontrol,
 		usb_audio_err(chip,
 			"cannot get connectors status: req = %#x, wValue = %#x, wIndex = %#x, type = %d\n",
 			UAC_GET_CUR, validx, idx, cval->val_type);
-		return ret;
+		return filter_error(cval, ret);
 	}
 
 	ucontrol->value.integer.value[0] = val;