[ALSA] sound: ca0106_mixer.c fix shadowed variable warnings

Change the variable err to _err within the ADD_CTLS macro to avoid
shadowing the local variable.

sound/pci/ca0106/ca0106_mixer.c:710:2: warning: symbol 'err' shadows an earlier one
sound/pci/ca0106/ca0106_mixer.c:663:6: originally declared here
sound/pci/ca0106/ca0106_mixer.c:712:3: warning: symbol 'err' shadows an earlier one
sound/pci/ca0106/ca0106_mixer.c:663:6: originally declared here
sound/pci/ca0106/ca0106_mixer.c:721:3: warning: symbol 'err' shadows an earlier one
sound/pci/ca0106/ca0106_mixer.c:663:6: originally declared here

Signed-off-by: Harvey Harrison <harvey.harrison@gmail.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
diff --git a/sound/pci/ca0106/ca0106_mixer.c b/sound/pci/ca0106/ca0106_mixer.c
index 94618ec..3025ed1 100644
--- a/sound/pci/ca0106/ca0106_mixer.c
+++ b/sound/pci/ca0106/ca0106_mixer.c
@@ -650,11 +650,11 @@
 
 #define ADD_CTLS(emu, ctls)						\
 	do {								\
-		int i, err;						\
+		int i, _err;						\
 		for (i = 0; i < ARRAY_SIZE(ctls); i++) {		\
-			err = snd_ctl_add(card, snd_ctl_new1(&ctls[i], emu)); \
-			if (err < 0)					\
-				return err;				\
+			_err = snd_ctl_add(card, snd_ctl_new1(&ctls[i], emu)); \
+			if (_err < 0)					\
+				return _err;				\
 		}							\
 	} while (0)