hwmon: (pmbus/max16601) Add support for MAX16508

hwmon: (pmbus/max16601) Add support for MAX16508

MAX16508 is quite similar to MAX16601, except that it does not support
the DEFAULT_NUM_POP register and we thus can not dynamically determine
the number of populated phases.

Cc: Alex Qiu <xqiu@google.com>
Cc: Ugur Usug <Ugur.Usug@maximintegrated.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20210125185327.93282-2-linux@roeck-us.net
Reviewed-by: Alex Qiu <xqiu@google.com>
Tested-by: Alex Qiu <xqiu@google.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>