ARM: dts: mvebu: add missing interrupt to 98dx4251 switch

The 98dx4251 has 4 interrupts for the packet processor whereas the
98dx3236 and 98dx3336 only have 3.
Signed-off-by: Chris Packham <chris.packham@alliedtelesis.co.nz>
Signed-off-by: Gregory CLEMENT <gregory.clement@free-electrons.com>

arch/arm/boot/dts/armada-xp-98dx4251.dtsi

@@ -87,4 +87,5 @@ sdio_pins: sdio-pins {
 
 &pp0 {
 	compatible = "marvell,prestera-98dx4251";
+	interrupts = <33>, <34>, <35>, <36>;
 };