ALSA: pci/aw2-saa7146: remove 'set but not used' warning

ALSA: pci/aw2-saa7146: remove 'set but not used' warning

Fix W=1 warning by nothing variable as always unused.

sound/pci/aw2/aw2-saa7146.c: In function ‘snd_aw2_saa7146_interrupt’:
sound/pci/aw2/aw2-saa7146.c:333:15: warning: variable ‘iicsta’ set but
not used [-Wunused-but-set-variable]
  333 |  unsigned int iicsta;
      |               ^~~~~~

Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Link: https://lore.kernel.org/r/20200702193604.169059-8-pierre-louis.bossart@linux.intel.com
Signed-off-by: Takashi Iwai <tiwai@suse.de>