[ARM] Orion: top-level IRQs are level-triggered

Make it clear that Orion top-level IRQs are level-triggered.  This
means that we don't need an ->ack() handler, or at least, we don't
need the ->ack() handler (or the acking part of the ->mask_ack()
handler) to actually do anything.

Given that, we might as well point our ->mask_ack() handler at the
->mask() handler instead of providing a dummy ->ack() handler, since
providing a ->mask_ack() handler on level IRQ sources will prevent
->ack() from ever being called.

Signed-off-by: Lennert Buytenhek <buytenh@marvell.com>
Acked-by: Russell King <linux@arm.linux.org.uk>

arch/arm/plat-orion/irq.c

@@ -36,8 +36,8 @@ static void orion_irq_unmask(u32 irq)
 
 static struct irq_chip orion_irq_chip = {
 	.name		= "orion_irq",
-	.ack		= orion_irq_mask,
 	.mask		= orion_irq_mask,
+	.mask_ack	= orion_irq_mask,
 	.unmask		= orion_irq_unmask,
 };
 
@@ -59,6 +59,7 @@ void __init orion_irq_init(unsigned int irq_start, void __iomem *maskaddr)
 		set_irq_chip(irq, &orion_irq_chip);
 		set_irq_chip_data(irq, maskaddr);
 		set_irq_handler(irq, handle_level_irq);
+		irq_desc[irq].status |= IRQ_LEVEL;
 		set_irq_flags(irq, IRQF_VALID);
 	}
 }