pinctrl: renesas: rzg2l: Add suspend/resume support for pull up/down

The Renesas RZ/G3S supports a power-saving mode where power to most of
the SoC components is lost, including the PIN controller.  Save and
restore the pull-up/pull-down register contents to ensure the
functionality is preserved after a suspend/resume cycle.

Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
Reviewed-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/20250205100116.2032765-1-claudiu.beznea.uj@bp.renesas.com


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