arm64: dts: renesas: r8a774e1: Add operating points

arm64: dts: renesas: r8a774e1: Add operating points

The RZ/G2H (r8a774e1) comes with two clusters of processors, similarly to
the r8a774a1. The first cluster is made of A57s, the second cluster is made
of A53s.

The operating points for the cluster with the A57s are:

Frequency | Voltage
----------|---------
500 MHz   | 0.82V
1.0 GHz   | 0.82V
1.5 GHz   | 0.82V

The operating points for the cluster with the A53s are:

Frequency | Voltage
----------|---------
800 MHz   | 0.82V
1.0 GHz   | 0.82V
1.2 GHz   | 0.82V

This patch adds the definitions for the operating points to the SoC
specific DT.

Signed-off-by: Marian-Cristian Rotariu <marian-cristian.rotariu.rb@bp.renesas.com>
Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Link: https://lore.kernel.org/r/1594811350-14066-2-git-send-email-prabhakar.mahadev-lad.rj@bp.renesas.com
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>