xfs: fix misspelled S_IS...()

mode_t is not a bitmap...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/xfs/linux-2.6/xfs_ioctl.c b/fs/xfs/linux-2.6/xfs_ioctl.c
index 14fc00e..f7ce7de 100644
--- a/fs/xfs/linux-2.6/xfs_ioctl.c
+++ b/fs/xfs/linux-2.6/xfs_ioctl.c
@@ -265,7 +265,7 @@
 		return PTR_ERR(filp);
 	}
 
-	if (inode->i_mode & S_IFREG) {
+	if (S_ISREG(inode->i_mode)) {
 		filp->f_flags |= O_NOATIME;
 		filp->f_mode |= FMODE_NOCMTIME;
 	}