vfs: make do_kern_mount() static

the only user outside of fs/namespace.c has died

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/namespace.c b/fs/namespace.c
index ed21ac4..7a8f949 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -1929,7 +1929,7 @@
 	return ERR_PTR(err);
 }
 
-struct vfsmount *
+static struct vfsmount *
 do_kern_mount(const char *fstype, int flags, const char *name, void *data)
 {
 	struct file_system_type *type = get_fs_type(fstype);
@@ -1943,7 +1943,6 @@
 	put_filesystem(type);
 	return mnt;
 }
-EXPORT_SYMBOL_GPL(do_kern_mount);
 
 /*
  * add a mount into a namespace's mount tree