The functions tpm_backend_thread_tpm_reset() and iothread_find()
are completely unused, let's remove them.

Signed-off-by: Thomas Huth <huth@tuxfamily.org>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>