Add chvgpio that supports the gpio driver found on Intel z8000 series system on chips.
This driver is based on the chvgpio driver from OpenBSD heavily refactored to match
FreeBSD gpio subsystem.
This revision does not support the interupt mechanisms on the gpio controller. The
hardware I have requires other devices drivers before I will be able to test these.
There is a test program here:
that controls the gpio connect fan in my Cherryview laptop (GPD Pocket)