ARM: dts: Fix elm interrupt compiler warning

Looks like the interrupt property is missing the controller and level
information causing:

Warning (interrupts_property): interrupts size is (4), expected multiple
of 12 in /ocp/elm@48078000

Signed-off-by: Tony Lindgren <tony@atomide.com>

arch/arm/boot/dts/omap4.dtsi

@@ -398,7 +398,7 @@
 		elm: elm@48078000 {
 			compatible = "ti,am3352-elm";
 			reg = <0x48078000 0x2000>;
-			interrupts = <4>;
+			interrupts = <GIC_SPI 4 IRQ_TYPE_LEVEL_HIGH>;
 			ti,hwmods = "elm";
 			status = "disabled";
 		};