dt-bindings: arm: renesas: Document Renesas RZ/G2UL SMARC EVK

Document the Renesas SMARC EVK board which is based on the Renesas
RZ/G2UL Type-1 (R9A07G043U11) SoC.  The SMARC EVK consists of an
RZ/G2UL Type-1 SoM module and a SMARC carrier board.  The SoM module
sits on top of the carrier board.

Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com>
Link: https://lore.kernel.org/r/20220402073234.24625-1-biju.das.jz@bp.renesas.com


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