hwmon: (adt7462) Use error value returned from find_trange_value()

find_trange_value() returns -ENODEV in case of errors, only to have it
ignored and replaced with -EINVAL. Make it return -EINVAL and use it.

Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Reviewed-by: Jean Delvare <khali@linux-fr.org>