switch vfs_mkdir() and ->mkdir() to umode_t

vfs_mkdir() gets int, but immediately drops everything that might not
fit into umode_t and that's the only caller of ->mkdir()...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/9p/vfs_inode.c b/fs/9p/vfs_inode.c
index 2310cc9..3e54900 100644
--- a/fs/9p/vfs_inode.c
+++ b/fs/9p/vfs_inode.c
@@ -785,7 +785,7 @@
  *
  */
 
-static int v9fs_vfs_mkdir(struct inode *dir, struct dentry *dentry, int mode)
+static int v9fs_vfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
 {
 	int err;
 	u32 perm;