[crypto] Mark permanent certificates as permanent

Signed-off-by: Michael Brown <mcb30@ipxe.org>

src/crypto/certstore.c

 		 * permanent reference to it.
 		 */
 		certstore_add ( cert );
+		cert->flags |= X509_FL_PERMANENT;
 		DBGC ( &certstore, "CERTSTORE permanent certificate %d is %s\n",
 		       i, x509_name ( cert ) );
 	}