Add the driver to monitor Inspur Power System power supplies
with hwmon over pmbus.

This driver adds sysfs attributes for additional power supply data,
including vendor, model, part_number, serial number,
firmware revision, hardware revision, and psu mode(active/standby).
Signed-off-by: NJohn Wang <wangzqbj@inspur.com>
Reviewed-by: NJoel Stanley <joel@jms.id.au>
Link: https://lore.kernel.org/r/20190819091509.29276-1-wangzqbj@inspur.comSigned-off-by: NGuenter Roeck <linux@roeck-us.net>