irqchip/bcm2836: Provide mask/unmask dummy methods for IPIs

Although it doesn't seem possible to disable individual mailbox
interrupts, we still need to provide some callbacks.

Fixes: 09eb672ce4fb ("irqchip/bcm2836: Configure mailbox interrupts as standard interrupts")
Reported-by: Marek Szyprowski <m.szyprowski@samsung.com>
Tested-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>

drivers/irqchip/irq-bcm2836.c

@@ -193,6 +193,8 @@ static void bcm2836_arm_irqchip_ipi_send_mask(struct irq_data *d,
 
 static struct irq_chip bcm2836_arm_irqchip_ipi = {
 	.name		= "IPI",
+	.irq_mask	= bcm2836_arm_irqchip_dummy_op,
+	.irq_unmask	= bcm2836_arm_irqchip_dummy_op,
 	.irq_eoi	= bcm2836_arm_irqchip_ipi_eoi,
 	.ipi_send_mask	= bcm2836_arm_irqchip_ipi_send_mask,
 };