crypto: simplify Hmac::HmacUpdate

This makes HmacUpdate slightly simpler and introduces a CHECK instead
of ignoring invalid input types.

PR-URL: https://github.com/nodejs/node/pull/22132


Reviewed-By: Jon Moss <me@jonathanmoss.me>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Ujjwal Sharma <usharma1998@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>