The MT8186 does not support configuring pin slew rate. This is evident
from both the datasheet, and the fact that the driver points the slew
rate register range at the GPIO direction register range.

Drop the bogus setting.

Fixes: 8b483bda ("pinctrl: add pinctrl driver on mt8186")
Signed-off-by: Chen-Yu Tsai <wenst@chromium.org>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Link: https://lore.kernel.org/r/20240131071910.3950450-1-wenst@chromium.orgSigned-off-by: Linus Walleij <linus.walleij@linaro.org>