soc: renesas: Add r8a77990 SYSC PM Domain Binding Definitions

This patch adds power domain indices for R-Car E3.

Signed-off-by: Takeshi Kihara <takeshi.kihara.df@renesas.com>
[shimoda: add commit log and SPDX-License-Identifier]
Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>