arm64: dts: renesas: Add initial SoC DTSI for the RZ/N2H SoC

Add the initial SoC DTSI for the Renesas RZ/N2H ("R9A09G087") SoC, below
is the list of blocks added:
  - EXT CLKs
  - 4x CA55
  - SCIF
  - CPG
  - GIC
  - ARMv8 Timer

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/20250617171957.162145-2-prabhakar.mahadev-lad.rj@bp.renesas.com


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