hwmon: (pmbus) Add support for MPS Multi-phase mp2856/mp2857 controller

Add support for mp2856/mp2857 device from Monolithic Power Systems, Inc.
(MPS) vendor. This is a dual-loop, digital, multi-phase,
modulation controller.

Signed-off-by: Peter Yin <peteryin.openbmc@gmail.com>
Signed-off-by: Potin Lai <potin.lai.pt@gmail.com>
Link: https://lore.kernel.org/r/20231211160519.21254-3-potin.lai.pt@gmail.com


[groeck: Fix checkpatch issues, use i2c_get_match_data()]
Signed-off-by: Guenter Roeck <linux@roeck-us.net>