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.comSigned-off-by: Takashi Iwai <tiwai@suse.de>

sound/pci/aw2/aw2-saa7146.c

@@ -330,7 +330,7 @@ void snd_aw2_saa7146_pcm_trigger_stop_capture(struct snd_aw2_saa7146 *chip,
 irqreturn_t snd_aw2_saa7146_interrupt(int irq, void *dev_id)
 {
 	unsigned int isr;
-	unsigned int iicsta;
+	__always_unused unsigned int iicsta;
 	struct snd_aw2_saa7146 *chip = dev_id;
 
 	isr = READREG(ISR);