cert-to-efi-hash-list: fix for openssl 1.1

Can't dereference the cert any more.  Unfortunately now there's no API
to get the cert->cert_info any more (thanks openssl!).  Fortunately we
can fiddle it with i2d_re_X509_tbs.

Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>