pinctrl: starfive: Use existing variable gpio

Use the existing variable "gpio", instead of obtaining the hwirq number
again.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Emil Renner Berthing <emil.renner.berthing@canonical.com>
Link: https://lore.kernel.org/r/3b6b8597792a393d0f21b8489dd933663dfd2b90.1669045778.git.geert+renesas@glider.be


Signed-off-by: Linus Walleij <linus.walleij@linaro.org>