ALSA: pci/asihpi: remove 'set but not used' warning

ALSA: pci/asihpi: remove 'set but not used' warning

Fix W=1 warnings, mark variables as __always_unused

sound/pci/asihpi/asihpi.c: In function ‘snd_asihpi_tuner_band_get’:
sound/pci/asihpi/asihpi.c:1907:6: warning: variable ‘num_bands’ set
but not used [-Wunused-but-set-variable]
 1907 |  u32 num_bands;
      |      ^~~~~~~~~
sound/pci/asihpi/asihpi.c: In function ‘snd_asihpi_tuner_band_put’:
sound/pci/asihpi/asihpi.c:1934:6: warning: variable ‘num_bands’ set
but not used [-Wunused-but-set-variable]
 1934 |  u32 num_bands;
      |      ^~~~~~~~~

Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Link: https://lore.kernel.org/r/20200702193604.169059-6-pierre-louis.bossart@linux.intel.com
Signed-off-by: Takashi Iwai <tiwai@suse.de>