ALSA: ice1724: Fix uninitialized variable access

Spotted by coverity CIDs 751505 and 751506.

Signed-off-by: Takashi Iwai <tiwai@suse.de>
diff --git a/sound/pci/ice1712/wm8776.c b/sound/pci/ice1712/wm8776.c
index 5227cb0..e66c0da 100644
--- a/sound/pci/ice1712/wm8776.c
+++ b/sound/pci/ice1712/wm8776.c
@@ -526,7 +526,8 @@
 	}
 	if (wm->ctl[n].flags & WM8776_FLAG_INVERT) {
 		val1 = wm->ctl[n].max - (val1 - wm->ctl[n].min);
-		val2 = wm->ctl[n].max - (val2 - wm->ctl[n].min);
+		if (wm->ctl[n].flags & WM8776_FLAG_STEREO)
+			val2 = wm->ctl[n].max - (val2 - wm->ctl[n].min);
 	}
 	ucontrol->value.integer.value[0] = val1;
 	if (wm->ctl[n].flags & WM8776_FLAG_STEREO)