dt-bindings: power: Add r8a774b1 SYSC power domain definitions

This patch adds power domain indices for the RZ/G2N (a.k.a r8a774b1)
SoC.

Signed-off-by: Biju Das <biju.das@bp.renesas.com>
Link: https://lore.kernel.org/r/1567666326-27373-1-git-send-email-biju.das@bp.renesas.com


Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>