hwmon: (pmbus/mp2975) Add OCP limit

Add support for PMBUS_IOUT_OC_FAULT_LIMIT.
Add a helper function to convert the limit to LINEAR11 format
and read data->info.phases[0] on MP2971 and MP2973 as well.

Signed-off-by: Patrick Rudolph <patrick.rudolph@9elements.com>
Signed-off-by: Naresh Solanki <Naresh.Solanki@9elements.com>
Link: https://lore.kernel.org/r/20230714135124.2645339-8-Naresh.Solanki@9elements.com


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