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>

net/rfkill/core.c

@@ -1351,11 +1351,11 @@ static long rfkill_fop_ioctl(struct file *file, unsigned int cmd,
 			     unsigned long arg)
 {
 	struct rfkill_data *data = file->private_data;
-	int ret = -ENOSYS;
+	int ret = -ENOTTY;
 	u32 size;
 
 	if (_IOC_TYPE(cmd) != RFKILL_IOC_MAGIC)
-		return -ENOSYS;
+		return -ENOTTY;
 
 	mutex_lock(&data->mtx);
 	switch (_IOC_NR(cmd)) {