ASoC: core: Fix compile warning with CONFIG_DEBUG_FS=n

Paper over a compile warning:
  sound/soc/soc-pcm.c:1185:8: warning: unused variable ‘name’

Fixes: 0632fa04 ("ASoC: core: Fix pcm code debugfs error")
Signed-off-by: NTakashi Iwai <tiwai@suse.de>
Link: https://lore.kernel.org/r/20191107134833.1502-1-tiwai@suse.deSigned-off-by: NMark Brown <broonie@kernel.org>

sound/soc/soc-pcm.c

@@ -1182,7 +1182,9 @@ static int dpcm_be_connect(struct snd_soc_pcm_runtime *fe,
 {
 	struct snd_soc_dpcm *dpcm;
 	unsigned long flags;
+#ifdef CONFIG_DEBUG_FS
 	char *name;
+#endif
 
 	/* only add new dpcms */
 	for_each_dpcm_be(fe, stream, dpcm) {