pinctrl: mediatek: add support for MTK_PULL_PD_TYPE

The MediaTek MT7988 SoC got some pins which only got configurable
pull-down but unlike previous designs there is no pull-up option.
Add new type MTK_PULL_PD_TYPE to support configuring such pins.

Signed-off-by: Daniel Golle <daniel@makrotopia.org>
Signed-off-by: Frank Wunderlich <frank-w@public-files.de>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Link: https://lore.kernel.org/20241217085435.9586-2-linux@fw-web.de


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