ALSA: snd-aloop - fix "PCM Slave Active" element read value

Simple coding fix.

Signed-off-by: Jaroslav Kysela <perex@perex.cz>
diff --git a/sound/drivers/aloop.c b/sound/drivers/aloop.c
index 2748fee..040030a 100644
--- a/sound/drivers/aloop.c
+++ b/sound/drivers/aloop.c
@@ -739,7 +739,7 @@
 {
 	struct loopback *loopback = snd_kcontrol_chip(kcontrol);
 	struct loopback_cable *cable = loopback->cables
-				[kcontrol->id.subdevice][kcontrol->id.device];
+			[kcontrol->id.subdevice][kcontrol->id.device ^ 1];
 	unsigned int val = 0;
 
 	if (cable != NULL)