hwmon: Deal with errors from the thermal subsystem

If the thermal subsystem returne -EPROBE_DEFER or any other error
when hwmon calls devm_thermal_zone_of_sensor_register(), this is
silently ignored.

I ran into this with an incorrectly defined thermal zone, making
it non-existing and thus this call failed with -EPROBE_DEFER
assuming it would appear later. The sensor was still added
which is incorrect: sensors must strictly be added after the
thermal zones, so deferred probe must be respected.

Fixes: d560168b

 ("hwmon: (core) New hwmon registration API")
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>