arm64: dts: renesas: rzg3s-smarc-switches: Add a header to describe different switches

arm64: dts: renesas: rzg3s-smarc-switches: Add a header to describe different switches

There are different switches available on both the RZ/G3S SMARC Module and
RZ SMARC Carrier II boards. These switches are used to route different SoC
signals to different parts available on board.

These switches are described in device trees through macros. These macros
are set accordingly such that the resulted compiled dtb to describe the
on-board switches states.

The SCIF1 depends on the state of the SW_CONFIG3 and SW_OPT_MUX4 switches.
SCIF1 can be enabled through a device tree overlay. To manage all switches
in a unified state and allow users to configure the output device tree, add
a file that contains all switch definitions and states.

Commit prepares the code to enable SCIF1 on the RZ/G3S overlay.

Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/20250120130936.1080069-3-claudiu.beznea.uj@bp.renesas.com
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>