switch may_mknod() to umode_t

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/namei.c

@@ -2472,7 +2472,7 @@ int vfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev)
 	return error;
 }
 
-static int may_mknod(mode_t mode)
+static int may_mknod(umode_t mode)
 {
 	switch (mode & S_IFMT) {
 	case S_IFREG: