buffer: remove error for malformatted hex string

Remove error message when a hex string of an incorrect length is sent
to .write() or .fill().

PR-URL: https://github.com/nodejs/node/pull/12012
Fixes: https://github.com/nodejs/node/issues/3770


Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Sakthipriyan Vairamani <thechargingvolcano@gmail.com>