hwmon: (pwm-fan) Check return value from devm_add_action_or_reset

devm_add_action_or_reset() can fail due to a memory allocation failure.
Check for it and return the error if that happens.

Fixes: 37bcec5d ("hwmon: (pwm-fan) Use devm_thermal_of_cooling_device_register")
Signed-off-by: Guenter Roeck <linux@roeck-us.net>