hwmon: (applesmc) Silence uninitialized warnings

Some error paths do not set a result, leading to the (false)
assumption that the value may be used uninitialized. Set results for
those paths as well.

Signed-off-by: Henrik Rydberg <rydberg@euromail.se>
Signed-off-by: Guenter Roeck <guenter.roeck@ericsson.com>