Fixed the compile warning regarding the unused function when built
with CONFIG_PM=n:
  sound/pci/hda/hda_intel.c:1905: warning: ‘snd_hda_codecs_inuse’ defined but not used

snd_hda_codecs_inuse() is used only in the resume callback.
Signed-off-by: NTakashi Iwai <tiwai@suse.de>