crypto: remove unnecessary template class

I came across this template class but I don't understand why it is
there. It is not used in the template specialization following it.

I just wanted to bring it up just in case this is something that
has been overlooked.

PR-URL: https://github.com/nodejs/node/pull/12993


Reviewed-By: Fedor Indutny <fedor@indutny.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>