net: small code cleanup

`options` is already a param of the function.

PR-URL: https://github.com/nodejs/node/pull/3943


Reviewed-By: Evan Lucas <evanlucas@me.com>
Reviewed-By: Michaël Zasso <mic.besace@gmail.com>
Reviewed-By: Myles Borins <myles.borins@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>