lib: remove unnecessary parameter for assertCrypto()

The `exports` parameter is unnecessary.

PR-URL: https://github.com/nodejs/node/pull/10834


Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Brian White <mscdex@mscdex.net>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Sam Roberts <sam@strongloop.com>