hwmon: (pmbus/mp2975) Use i2c_get_match_data()

Use preferred i2c_get_match_data() instead of of_device_get_match_data()
to get the driver match data. With this, adjust the includes to explicitly
include the correct headers.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20240325120952.3019767-4-andriy.shevchenko@linux.intel.com


[groeck: Dropped __maybe_unused from mp2975_of_match]
Signed-off-by: Guenter Roeck <linux@roeck-us.net>