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/arch/arm64/Kconfig b/arch/arm64/Kconfig
index ac9afde..1f49c288 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -13,6 +13,7 @@
 	select ARM_GIC
 	select AUDIT_ARCH_COMPAT_GENERIC
 	select ARM_GIC_V3
+	select ARM_GIC_V3_ITS if PCI_MSI
 	select BUILDTIME_EXTABLE_SORT
 	select CLONE_BACKWARDS
 	select COMMON_CLK