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/fat/namei_vfat.c b/fs/fat/namei_vfat.c
index a87a656..fde2eda 100644
--- a/fs/fat/namei_vfat.c
+++ b/fs/fat/namei_vfat.c
@@ -870,7 +870,7 @@
 	return err;
 }
 
-static int vfat_mkdir(struct inode *dir, struct dentry *dentry, int mode)
+static int vfat_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
 {
 	struct super_block *sb = dir->i_sb;
 	struct inode *inode;