[ALSA] sound: ac97_pcm.c fix shadowed variable warning

err is always assigned before it is used, no need to declare another
inside the if statement.
sound/pci/ac97/ac97_pcm.c:577:7: warning: symbol 'err' shadows an earlier one
sound/pci/ac97/ac97_pcm.c:572:6: originally declared here

Signed-off-by: Harvey Harrison <harvey.harrison@gmail.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/pci/ac97/ac97_pcm.c

@@ -574,7 +574,6 @@ int snd_ac97_pcm_open(struct ac97_pcm *pcm, unsigned int rate,
 	r = rate > 48000;
 	bus = pcm->bus;
 	if (cfg == AC97_PCM_CFG_SPDIF) {
-		int err;
 		for (cidx = 0; cidx < 4; cidx++)
 			if (bus->codec[cidx] && (bus->codec[cidx]->ext_id & AC97_EI_SPDIF)) {
 				err = set_spdif_rate(bus->codec[cidx], rate);