ARM: dts: iwg23s-sbc: specify EtherAVB PHY IRQ

Specify  EtherAVB PHY IRQ  in the board specific device tree, now that we
have GPIO support.
Signed-off-by: Biju Das <biju.das@bp.renesas.com>
Reviewed-by: Fabrizio Castro <fabrizio.castro@bp.renesas.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>

arch/arm/boot/dts/r8a77470-iwg23s-sbc.dts

@@ -35,6 +35,8 @@ &avb {
 
 	phy3: ethernet-phy@3 {
 		reg = <3>;
+		interrupt-parent = <&gpio5>;
+		interrupts = <16 IRQ_TYPE_LEVEL_LOW>;
 		micrel,led-mode = <1>;
 	};
 };