src: remove unnecessary return statement

I think the code would be a little clearer if the return statement
was removed here since End() does not return any value and neither
does ParseHeader.

PR-URL: https://github.com/nodejs/node/pull/13094


Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: Sakthipriyan Vairamani <thechargingvolcano@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Refael Ackermann <refack@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Gibson Fahnestock <gibfahn@gmail.com>