pinctrl: renesas: rzg2l: Move pinconf_to_config_argument() call outside of switch cases

Refactor the `rzg2l_pinctrl_pinconf_set()` function by moving the call to
`arg = pinconf_to_config_argument(_configs[i])` to the beginning of the
loop. Previously, this call was redundantly made in most cases within the
switch statement.

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/20240829194841.84398-3-prabhakar.mahadev-lad.rj@bp.renesas.com


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