arm64: rk3399: pinctrl: Add gpio banks and fix iomux

Since r351187 the pinctrl driver need to know the gpio bank as it
directly attach the gpio driver to handle some setup that might
be present in the dts, add the gpio banks table for rk3399.
While here fix some IOMUX definition that prevented to boot
on RK3399 as pinctrl wasn't configured correctly.

Submitted by: mmel (original version)
MFC after: 2 weeks
MFC With: r351187