ASoC: soc-core: cleanup cppcheck warning at snd_soc_add_controls()

This patch cleanups below cppcheck warning.

sound/soc/soc-core.c:2239:6: style: The scope of the variable 'err' can be reduced. [variableScope]
 int err, i;
     ^
Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Link: https://lore.kernel.org/r/87r1fhyl6f.wl-kuninori.morimoto.gx@renesas.comSigned-off-by: Mark Brown <broonie@kernel.org>

sound/soc/soc-core.c

@@ -2237,12 +2237,11 @@ static int snd_soc_add_controls(struct snd_card *card, struct device *dev,
 	const struct snd_kcontrol_new *controls, int num_controls,
 	const char *prefix, void *data)
 {
-	int err, i;
+	int i;
 
 	for (i = 0; i < num_controls; i++) {
 		const struct snd_kcontrol_new *control = &controls[i];
-
-		err = snd_ctl_add(card, snd_soc_cnew(control, data,
+		int err = snd_ctl_add(card, snd_soc_cnew(control, data,
 							 control->name, prefix));
 		if (err < 0) {
 			dev_err(dev, "ASoC: Failed to add %s: %d\n",