arm64: dts: renesas: v3msk: specify EtherAVB PHY IRQ

Specify EtherAVB PHY IRQ in the V3M Starter Kit board's device tree, now
that we have the GPIO support (previously phylib had to resort to polling).

Signed-off-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>