arm64: dts: renesas: r8a774a1: Connect Ethernet-AVB to IPMMU-DS0

Add IPMMU-DS0 to the Ethernet-AVB device node.

Based on work by Magnus Damm for the r8a7795.

Signed-off-by: Biju Das <biju.das@bp.renesas.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>