ALSA: snd-aloop - fix the "PCM Playback Channels" kcontrol

Obvious copy-and-paste error.

Signed-off-by: Jaroslav Kysela <perex@perex.cz>
diff --git a/sound/drivers/aloop.c b/sound/drivers/aloop.c
index 3123a15..f2b8f86 100644
--- a/sound/drivers/aloop.c
+++ b/sound/drivers/aloop.c
@@ -809,7 +809,7 @@
 	
 	ucontrol->value.integer.value[0] =
 		loopback->setup[kcontrol->id.subdevice]
-			       [kcontrol->id.device].rate;
+			       [kcontrol->id.device].channels;
 	return 0;
 }