ALSA: hda/sigmatel: Fix unused variable warning for beep power change

ALSA: hda/sigmatel: Fix unused variable warning for beep power change

commit d718e9809d90339d2a2754e20d29b72a0c04cc0d upstream.

The newly added stac_check_power_status() caused a compile warning
when CONFIG_SND_HDA_INPUT_BEEP is disabled.  Fix it.

Fixes: c25ca73d3991 ("ALSA: hda/sigmatel: Keep power up while beep is enabled")
Reported-by: kernel test robot <lkp@intel.com>
Link: https://lore.kernel.org/r/20220905130630.2845-1-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>