hwmon: (dell-smm) Return -ENOIOCTLCMD instead of -EINVAL

Returning -ENOIOCTLCMD gives the callers a better
hint of what went wrong and is the recommended
behavior.

Signed-off-by: Armin Wolf <W_Armin@gmx.de>
Acked-by: Pali Rohár <pali@kernel.org>
Link: https://lore.kernel.org/r/20211021190531.17379-4-W_Armin@gmx.de


Signed-off-by: Guenter Roeck <linux@roeck-us.net>