hwmon: (pmbus/mp2975) Constify local pointers to pmbus_driver_info

Constify the local variables pointing to "struct pmbus_driver_info" and
other encoding params to annotate the function is not modifying pointed
data.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20240325120952.3019767-3-andriy.shevchenko@linux.intel.com


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