tpm: Modify DPRINTF to enable -Wformat checking

Modify DPRINTF to always enable -Wformat checking.

Signed-off-by: Stefan Berger <stefanb@linux.vnet.ibm.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
