pinctrl: mediatek: add PUPD/R0/R1 support for MT7623

The pins for the MMC controller weren't being set up correctly because the
pinctrl driver only sets the GPIO pullup/pulldown config and doesn't
handle the special cases with PUPD/R0/R1 control.

Signed-off-by: David Woodhouse <dwmw2@infradead.org>
Tested-by: Frank Wunderlich <frank-w@public-files.de>