[ALSA] aoa: feature gpio layer: fix IRQ access

The IRQ rework caused some hiccups here, in some cases we call
get_irq without a device node. This patch makes it catch that
case and return NO_IRQ when it happens, along with changing the
place where the irq is checked to check for NO_IRQ instead of -1.
Acked-by: Benjamin Herrenschmidt <[e-mail]>

Signed-off-by: Johannes Berg <[e-mail]>
Signed-off-by: Takashi Iwai <[e-mail]>
Signed-off-by: Jaroslav Kysela <[e-mail]>

sound/aoa/core/snd-aoa-gpio-feature.c

···
 
 static void get_irq(struct device_node * np, int *irqptr)
 {
-	*irqptr = irq_of_parse_and_map(np, 0);
+	if (np)
+		*irqptr = irq_of_parse_and_map(np, 0);
+	else
+		*irqptr = NO_IRQ;
 }
 
 /* 0x4 is outenable, 0x1 is out, thus 4 or 5 */
···
 		return -EINVAL;
 	}
 
-	if (irq == -1)
+	if (irq == NO_IRQ)
 		return -ENODEV;
 
 	mutex_lock(&notif->mutex);