tls_valid_group: Add missing dereference of okfortls13
tls_valid_group: Add missing dereference of okfortls13

Fixes #14153

Reviewed-by: Matt Caswell <1fa2ef4755a9226cb9a0a4840bd89b158ac71391@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/14154)

openssl/openssl,openssl/openssl,openssl/openssl,openssl/openssl,openssl/openssl,openssl/openssl