Remove a further kludge from __do_follow_link()

Remove a further kludge from __do_follow_link() as it's no longer required with
the automount code.

This reverts the non-helper-function parts of
051d3812, which breaks union mounts.

Reported-by:  <vaurora@redhat.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>