hwmon: (pmbus/lm25066) Ignore byte writes to non-zero pages

pmbus_clear_faults() attempts to clear faults on non-existing real pages.
As a result, the command error bit in the status register is set, and faults
are not really cleared.

All byte writes to non-zero pages are requests to clear the status register
on that page. Since non-zero pages are virtual and do not exist on the chip,
there is nothing to do, and such requests have to be ignored. This fixes
above problem.

Signed-off-by: Guenter Roeck <guenter.roeck@ericsson.com>
Reviewed-by: Robert Coulson <robert.coulson@ericsson.com>