ktls: Remove the socket parameter to ktls_ocf_try()

The socket is unused, and not passing it means that there's less to
think about when considering how KTLS is synchronized with the rest of
the socket code. No functional change intended.

Reviewed by: gallatin
MFC after: 2 weeks
Sponsored by: Klara, Inc.
Sponsored by: Stormshield
Differential Revision: https://reviews.freebsd.org/D45675