ARM: mvebu: the MPIC now provides MSI controller features

Adds the 'msi-controller' property to the main interrupt controller
Device Tree node, to indicate that it can now behave as a MSI
controller.
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Reviewed-by: Thierry Reding <thierry.reding@gmail.com>
Tested-by: Daniel Price <daniel.price@gmail.com>
Acked-by: Gregory CLEMENT <gregory.clement@free-electrons.com>
Signed-off-by: Jason Cooper <jason@lakedaemon.net>

arch/arm/boot/dts/armada-370-xp.dtsi

@@ -113,6 +113,7 @@ mpic: interrupt-controller@20000 {
 				#interrupt-cells = <1>;
 				#size-cells = <1>;
 				interrupt-controller;
+				msi-controller;
 			};
 
 			coherency-fabric@20200 {