hwmon: pmbus: mpq8785: Prepare driver for multiple device support

Refactor the driver to support multiple Monolithic Power Systems devices.
Introduce chip ID handling based on device tree matching.

No functional changes intended.

Signed-off-by: Pawel Dembicki <paweldembicki@gmail.com>
Link: https://lore.kernel.org/r/20250511035701.2607947-3-paweldembicki@gmail.com


Signed-off-by: Guenter Roeck <linux@roeck-us.net>