staging/lustre: Properly cast ll_fid2path argument to __user in ll_dir_ioctl

This makes sparse happier.
Signed-off-by: Oleg Drokin <green@linuxhacker.ru>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/lustre/lustre/llite/dir.c

@@ -1736,7 +1736,7 @@ static long ll_dir_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 				    sizeof(struct ioc_changelog));
 		return rc;
 	case OBD_IOC_FID2PATH:
-		return ll_fid2path(inode, (void *)arg);
+		return ll_fid2path(inode, (void __user *)arg);
 	case LL_IOC_HSM_REQUEST: {
 		struct hsm_user_request	*hur;
 		ssize_t			 totalsize;