irqchip: Add Layerscape SCFG MSI controller support

Some kind of Freescale Layerscape SoC provides a MSI
implementation which uses two SCFG registers MSIIR and
MSIR to support 32 MSI interrupts for each PCIe controller.
The patch is to support it.

Signed-off-by: Minghuan Lian <Minghuan.Lian@nxp.com>
Tested-by: Alexander Stein <alexander.stein@systec-electronic.com>
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
diff --git a/drivers/irqchip/Makefile b/drivers/irqchip/Makefile
index e354b00c..8cedf90 100644
--- a/drivers/irqchip/Makefile
+++ b/drivers/irqchip/Makefile
@@ -66,3 +66,4 @@
 obj-$(CONFIG_IMX_GPCV2)			+= irq-imx-gpcv2.o
 obj-$(CONFIG_PIC32_EVIC)		+= irq-pic32-evic.o
 obj-$(CONFIG_MVEBU_ODMI)		+= irq-mvebu-odmi.o
+obj-$(CONFIG_LS_SCFG_MSI)		+= irq-ls-scfg-msi.o