xfs: get rid of open-coded S_ISREG(), etc.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/xfs/xfs_filestream.c b/fs/xfs/xfs_filestream.c
index 9124425..87fcece 100644
--- a/fs/xfs/xfs_filestream.c
+++ b/fs/xfs/xfs_filestream.c
@@ -344,7 +344,7 @@
 	 * Either ip is a regular file and pip is a directory, or ip is a
 	 * directory and pip is NULL.
 	 */
-	ASSERT(ip && (((ip->i_d.di_mode & S_IFREG) && pip &&
+	ASSERT(ip && ((S_ISREG(ip->i_d.di_mode) && pip &&
 	               (pip->i_d.di_mode & S_IFDIR)) ||
 	              ((ip->i_d.di_mode & S_IFDIR) && !pip)));