ASoC: pcm: Fix unused variable warning

sound/soc/soc-pcm.c: In function ‘soc_pcm_set_msb’:
sound/soc/soc-pcm.c:307:11: warning: unused variable ‘i’ [-Wunused-variable]

Fixes: 0e2a3751 ('ASoC: pcm: Use wildcard msbits constraints')
Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/soc/soc-pcm.c

@@ -304,7 +304,7 @@ static bool soc_pcm_has_symmetry(struct snd_pcm_substream *substream)
 static void soc_pcm_set_msb(struct snd_pcm_substream *substream, int bits)
 {
 	struct snd_soc_pcm_runtime *rtd = substream->private_data;
-	int ret, i;
+	int ret;
 
 	if (!bits)
 		return;