hwmon: (pmbus/max16601) Add support for new revisions of MAX16508

New revisions of MAX16508 report MAX16508.xx or MAX16508y.xx as device ID,
but are functionally similar to MAX16508. Add support for those chip
variants.

Cc: Vlad Sytchenko <vsytch@google.com>
Cc: Steve Foreman <foremans@google.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>