arm64: dts: renesas: rzg2ul-smarc-som: Enable ADC on SMARC platform

Enable the ADC found on RZ/G2UL SMARC SoM.

Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com>
Link: https://lore.kernel.org/r/20220608173025.22792-3-biju.das.jz@bp.renesas.com


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