arm64: dts: renesas: rzg2ul-smarc: Include SoM DTSI into board DTS

Move including the rzg2ul-smarc-som.dtsi from the carrier board
rzg2ul-smarc.dtsi to the actual RZ/G2UL SMARC EVK board dts
r9a07g043u11-smarc.dts. Also move the SW_SW0_DEV_SEL and
SW_ET0_EN_N macros to board dts as they are used by SoM and carrier
board DTS/I.

This is in preparation of re-using the SoM and carrier board DTSIs
for RZ/Five SMARC EVK.

Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Link: https://lore.kernel.org/r/20220915165256.352843-2-prabhakar.mahadev-lad.rj@bp.renesas.com


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