arm64: dts: renesas: Add initial support for the Renesas RZ/T2H SoC

arm64: dts: renesas: Add initial support for the Renesas RZ/T2H SoC

Add the initial dtsi for the RZ/T2H SoC:
    - GIC
    - ARMv8-timer
    - CPG clock
    - SCI0 UART

also add arch/arm64/boot/dts/renesas/r9a09g077m44.dtsi, that keeps all 4
CPUs enabled, for consistency with later support of -m24 and -m04 SoC
revisions, that only have 2 and 1 Cortex-A55, respectively, and that
will use /delete-node/ to disable the missing CPUs.

Signed-off-by: Thierry Bultel <thierry.bultel.yh@bp.renesas.com>
Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/20250617162810.154332-2-prabhakar.mahadev-lad.rj@bp.renesas.com
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>