ALSA: hda/ca0132 - Fix superfluous unsigned check

Fix a warning by smatch,
 sound/pci/hda/patch_ca0132.c:714 dspio_send() warn: always true
 condition '(res >= 0) => (0-u32max >= 0)'

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
diff --git a/sound/pci/hda/patch_ca0132.c b/sound/pci/hda/patch_ca0132.c
index 467c9a1..7668388 100644
--- a/sound/pci/hda/patch_ca0132.c
+++ b/sound/pci/hda/patch_ca0132.c
@@ -1054,7 +1054,7 @@
 static int dspio_send(struct hda_codec *codec, unsigned int reg,
 		      unsigned int data)
 {
-	unsigned int res;
+	int res;
 	int retry = 50;
 
 	/* send bits of data specified by reg to dsp */