arm64: dts: renesas: v3msk: add EtherAVB pins

Add the (previously omitted) EtherAVB pin data to the V3M Starter Kit
board's device tree.

Signed-off-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>