irqchip: orion: clear bridge cause register on init

It is good practice to mask and clear pending irqs on init. We already
mask all irqs, so also clear the bridge irq cause register.

Signed-off-by: Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>
Tested-by: Ezequiel Garcia <ezequiel.garcia@free-electrons.com>
Cc: <stable@vger.kernel.org> # v3.10+
Signed-off-by: Jason Cooper <jason@lakedaemon.net>

drivers/irqchip/irq-orion.c

@@ -180,8 +180,9 @@ static int __init orion_bridge_irq_init(struct device_node *np,
 	gc->chip_types[0].chip.irq_mask = irq_gc_mask_clr_bit;
 	gc->chip_types[0].chip.irq_unmask = irq_gc_mask_set_bit;
 
-	/* mask all interrupts */
+	/* mask and clear all interrupts */
 	writel(0, gc->reg_base + ORION_BRIDGE_IRQ_MASK);
+	writel(0, gc->reg_base + ORION_BRIDGE_IRQ_CAUSE);
 
 	irq_set_handler_data(irq, domain);
 	irq_set_chained_handler(irq, orion_bridge_irq_handler);