dt-bindings: clock: renesas: Document RZ/G2UL SoC

Document the device tree binding for the Renesas RZ/G2UL Type-1
and Type-2 SoC. RZ/G2UL Type-2 has fewer clocks than RZ/G2UL Type-1
SoC.

Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com>
Reviewed-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20220315142915.17764-1-biju.das.jz@bp.renesas.com


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