greybus: gpio.c: fix a bad irq number

When it receive an interrupt, the function gb_gpio_request_recv doesn't
use the good gpio number to get the irq number. Then, the expected irq is never fired.
Signed-off-by: Greg Kroah-Hartman <greg@kroah.com>

drivers/staging/greybus/gpio.c

@@ -421,7 +421,7 @@ static void gb_gpio_request_recv(u8 type, struct gb_operation *op)
 		pr_err("Unsupported hw irq %d\n", event->which);
 		return;
 	}
-	irq = gpio_to_irq(ggc->irq_base + event->which);
+	irq = gpio_to_irq(ggc->chip.base + event->which);
 	desc = irq_to_desc(irq);
 
 	/* Dispatch interrupt */