hwmon: (pmbus/ucd9000) Add support for UCD90320 Power Sequencer

Add support for the UCD90320 chip and its expanded set of GPIO pins.

Signed-off-by: Jim Wright <wrightj@linux.vnet.ibm.com>
Link: https://lore.kernel.org/r/20191205232411.21492-3-wrightj@linux.vnet.ibm.com
Signed-off-by: Guenter Roeck <linux@roeck-us.net>