VFS: Unexport do_kern_mount() and clean up simple_pin_fs()

Replace all module uses with the new vfs_kern_mount() interface, and fix up
simple_pin_fs().

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
diff --git a/include/linux/fs.h b/include/linux/fs.h
index f813bc8..eca70cf 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1763,7 +1763,7 @@
 struct tree_descr { char *name; const struct file_operations *ops; int mode; };
 struct dentry *d_alloc_name(struct dentry *, const char *);
 extern int simple_fill_super(struct super_block *, int, struct tree_descr *);
-extern int simple_pin_fs(char *name, struct vfsmount **mount, int *count);
+extern int simple_pin_fs(struct file_system_type *, struct vfsmount **mount, int *count);
 extern void simple_release_fs(struct vfsmount **mount, int *count);
 
 extern ssize_t simple_read_from_buffer(void __user *, size_t, loff_t *, const void *, size_t);