irqchip: GICv3: ITS: enable compilation of the ITS driver

Get the show on the road...

Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Link: https://lkml.kernel.org/r/1416839720-18400-13-git-send-email-marc.zyngier@arm.com
Signed-off-by: Jason Cooper <jason@lakedaemon.net>
diff --git a/drivers/irqchip/Kconfig b/drivers/irqchip/Kconfig
index 4631685..aaa260b 100644
--- a/drivers/irqchip/Kconfig
+++ b/drivers/irqchip/Kconfig
@@ -16,6 +16,10 @@
 	select MULTI_IRQ_HANDLER
 	select IRQ_DOMAIN_HIERARCHY
 
+config ARM_GIC_V3_ITS
+	bool
+	select PCI_MSI_IRQ_DOMAIN
+
 config ARM_NVIC
 	bool
 	select IRQ_DOMAIN