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: Takashi Iwai <tiwai@suse.de>
Link: https://lore.kernel.org/r/20191107134833.1502-1-tiwai@suse.de
Signed-off-by: Mark Brown <broonie@kernel.org>