soc: renesas: Add SYSC driver for Renesas RZ family

soc: renesas: Add SYSC driver for Renesas RZ family

The RZ/G3S system controller (SYSC) has various registers that control
different functionalities.  One of the exposed register offers
information about the SoC identification.

Add a driver that identifies the SoC.  Later the driver will be extended
with other functionalities.

Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
Signed-off-by: John Madieu <john.madieu.xa@bp.renesas.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/20250128031342.52675-2-john.madieu.xa@bp.renesas.com
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>