hwmon: (pmbus) Driver for Delta power supplies Q54SJ108A2

The driver supports Q54SJ108A2 series modules of Delta.
Standard attributes are in sysfs, and other attributes are in debugfs.

Signed-off-by: xiao.ma <xiao.mx.ma@deltaww.com>
Link: https://lore.kernel.org/r/20201202025900.1842-1-max701@126.com
[groeck: Replaced spaces with tabs, dropped excessive spaces,
 fixed module prefix in documentation]
Signed-off-by: Guenter Roeck <linux@roeck-us.net>