vsock: fix the error return when an invalid ioctl command is used

Currently when an invalid ioctl command is used the error return
is -EINVAL.  Fix this by returning the correct error -ENOIOCTLCMD.
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

net/vmw_vsock/af_vsock.c

@@ -2072,7 +2072,7 @@ static long vsock_dev_do_ioctl(struct file *filp,
 		break;
 
 	default:
-		retval = -EINVAL;
+		retval = -ENOIOCTLCMD;
 	}
 
 	return retval;