swtpm_cert: use hashAlgo as parameter for signing certificates

Ceritficates for a TPM 2 have to be signed using SHA256 and those for
a TPM 1.2 have to be signed using SHA1 (following specs). We can use
either of these algorithms when using the GnuTLS TPM support since it
will create the hash and have the TPM 1.2 sign whatever it created.

Signed-off-by: Stefan Berger <stefanb@linux.ibm.com>

src/swtpm_cert/ek-cert.c

@@ -1542,9 +1542,9 @@ if (_err != GNUTLS_E_SUCCESS) {             \
     if (sigkey) {
         err = gnutls_x509_crt_sign2(crt, sigcert, sigkey, hashAlgo, 0);
     } else {
-        /* TPM 1.2 signs cert */
+        /* TPM 1.2 signs cert for a TPM 1.2 (SHA1) or TPM 2 (SHA256) */
         err = gnutls_x509_crt_privkey_sign(crt, sigcert, tpmkey,
-                                           GNUTLS_DIG_SHA1, 0);
+                                           hashAlgo, 0);
     }
     CHECK_GNUTLS_ERROR(err, "Could not sign the CRT: %s\n",
                        gnutls_strerror(err))