hwmon: (pmbus/pxe1610) don't bail out when not all pages are active

Certain VRs might be configured to use only the first output channel and
so the mode for the second will be 0. Handle this gracefully.

Fixes: b9fa0a3a

 ("hwmon: (pmbus/core) Add support for vid mode detection per page bases")
Signed-off-by: Paul Fertser <fercerpav@gmail.com>
Link: https://lore.kernel.org/r/20210416102926.13614-1-fercerpav@gmail.com


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