irqchip: gic-v2m: Add support for ARM GICv2m MSI(-X) doorbell

ARM GICv2m specification extends GICv2 to support MSI(-X) with
a new register frame. This allows a GICv2 based system to support
MSI with minimal changes.

Signed-off-by: Suravee Suthikulpanit <Suravee.Suthikulpanit@amd.com>
[maz: converted the driver to use stacked irq domains,
      updated changelog]
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Link: https://lkml.kernel.org/r/1416941243-7181-2-git-send-email-marc.zyngier@arm.com
Signed-off-by: Jason Cooper <jason@lakedaemon.net>
diff --git a/drivers/irqchip/Makefile b/drivers/irqchip/Makefile
index 2029e79..983634d 100644
--- a/drivers/irqchip/Makefile
+++ b/drivers/irqchip/Makefile
@@ -19,6 +19,7 @@
 obj-$(CONFIG_ARCH_SUNXI)		+= irq-sunxi-nmi.o
 obj-$(CONFIG_ARCH_SPEAR3XX)		+= spear-shirq.o
 obj-$(CONFIG_ARM_GIC)			+= irq-gic.o irq-gic-common.o
+obj-$(CONFIG_ARM_GIC_V2M)		+= irq-gic-v2m.o
 obj-$(CONFIG_ARM_GIC_V3)		+= irq-gic-v3.o irq-gic-common.o
 obj-$(CONFIG_ARM_GIC_V3_ITS)		+= irq-gic-v3-its.o
 obj-$(CONFIG_ARM_NVIC)			+= irq-nvic.o