pinctrl: renesas: rzg2l: Use gpiochip_populate_parent_fwspec_twocell helper

Because rzg2l_gpio_populate_parent_fwspec() and
gpiochip_populate_parent_fwspec_twocell() are identical.

Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/20241017113942.139712-3-prabhakar.mahadev-lad.rj@bp.renesas.com


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