Fixed typo in code comment.

[skip ci]

Reviewed-by: Tim Hudson <tjh@openssl.org>
Reviewed-by: Matthias St. Pierre <Matthias.St.Pierre@ncp-e.com>
Reviewed-by: Richard Levitte <levitte@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/9102)

(cherry picked from commit 87762939b508c7968d3c54d44c1319416c27603e)