arm64: dts: renesas: r8a774a1: Add CPU topology on r8a774a1 SoC

This patch adds the "cpu-map" into r8a774a1 composed of multi-cluster. This
definition is used to parse the cpu topology.

Based on work by Gaku Inami <gaku.inami.xw@bp.renesas.com> for r8a7796 SoC.

Signed-off-by: Biju Das <biju.das@bp.renesas.com>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>