ARM: dts: ixp42x: Expand syscon register range

We have at least 0x30 registers in the IXP42x syscon as
register 0x2c is actively used to read platform features.
Signed-off-by: NLinus Walleij <linus.walleij@linaro.org>

arch/arm/boot/dts/intel-ixp42x.dtsi

@@ -9,7 +9,7 @@
 	soc {
 		bus@c4000000 {
 			compatible = "intel,ixp42x-expansion-bus-controller", "syscon";
-			reg = <0xc4000000 0x28>;
+			reg = <0xc4000000 0x30>;
 		};
 
 		pci@c0000000 {