pinctrl: renesas: rzg2l: Make struct rzg2l_pinctrl_data::dedicated_pins constant

struct rzg2l_pinctrl_data::dedicated_pins is constant thus mark it so.

Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/20230912045157.177966-29-claudiu.beznea.uj@bp.renesas.com


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