ALSA: pci/es1938: remove 'set but not used' warning

Fix W=1 warning. Mark the 'audiostatus' variable as __always_unused.

sound/pci/es1938.c: In function ‘snd_es1938_interrupt’:
sound/pci/es1938.c:1622:24: warning: variable ‘audiostatus’ set but
not used [-Wunused-but-set-variable]
 1622 |  unsigned char status, audiostatus;
      |                        ^~~~~~~~~~~
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Link: https://lore.kernel.org/r/20200702193604.169059-19-pierre-louis.bossart@linux.intel.comSigned-off-by: Takashi Iwai <tiwai@suse.de>

sound/pci/es1938.c

@@ -1619,7 +1619,8 @@ static int snd_es1938_create(struct snd_card *card,
 static irqreturn_t snd_es1938_interrupt(int irq, void *dev_id)
 {
 	struct es1938 *chip = dev_id;
-	unsigned char status, audiostatus;
+	unsigned char status;
+	__always_unused unsigned char audiostatus;
 	int handled = 0;
 
 	status = inb(SLIO_REG(chip, IRQCONTROL));