pinctrl: renesas: rzg2l: Drop struct rzg2l_variable_pin_cfg

Drop the rzg2l_variable_pin_cfg struct and instead use the
RZG2L_VARIABLE_PIN_CFG_PACK() macro for the variable pin configuration.

Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Tested-by: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com> # on RZ/G3S
Link: https://lore.kernel.org/r/20240530173857.164073-5-prabhakar.mahadev-lad.rj@bp.renesas.com


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