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

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

Fix W=1 warnings by removing 2 unnecessary initializations and
removing a variable that's not used.

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 = 0;
      |      ^~~~~~~~~
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 = 0;
      |      ^~~~~~~~~
sound/pci/asihpi/asihpi.c: In function ‘snd_asihpi_mux_info’:
sound/pci/asihpi/asihpi.c:2164:6: warning: variable ‘err’ set but not
 used [-Wunused-but-set-variable]
 2164 |  int err;
      |      ^~~

Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Link: https://lore.kernel.org/r/20200702193604.169059-4-pierre-louis.bossart@linux.intel.com
Signed-off-by: Takashi Iwai <tiwai@suse.de>