rfkill: return ENOTTY on invalid ioctl

For unknown ioctls the correct error is
ENOTTY "Inappropriate ioctl for device".

ENOSYS as returned before should only be used to
indicate that a syscall is not available at all.

Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Reviewed-by: Przemek Kitszel <przemyslaw.kitszel@intel.com>
Link: https://lore.kernel.org/r/20231101-rfkill-ioctl-enosys-v1-1-5bf374fabffe@weissschuh.net


[in theory this breaks userspace API, but it was discussed and
 researched, and nothing found relying on the current behaviour]
Signed-off-by: Johannes Berg <johannes.berg@intel.com>