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/fs/binfmt_misc.c b/fs/binfmt_misc.c
index d73d755..c0a909e 100644
--- a/fs/binfmt_misc.c
+++ b/fs/binfmt_misc.c
@@ -55,6 +55,7 @@
 } Node;
 
 static DEFINE_RWLOCK(entries_lock);
+static struct file_system_type bm_fs_type;
 static struct vfsmount *bm_mnt;
 static int entry_count;
 
@@ -638,7 +639,7 @@
 	if (!inode)
 		goto out2;
 
-	err = simple_pin_fs("binfmt_misc", &bm_mnt, &entry_count);
+	err = simple_pin_fs(&bm_fs_type, &bm_mnt, &entry_count);
 	if (err) {
 		iput(inode);
 		inode = NULL;