Clean away needless VMS check

BIO_socket_ioctl is only implemented on VMS for VMS version 7.0 and
up, but since we only support version 7.1 and up, there's no need to
check the VMS version.

Reviewed-by: Rich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/3448)