oce(4): deprecate

The Emulex OneConnect NIC driver hasn't seen any commits other than ioctl
bug fixes (some severe) and sweeping commits since 2016. There is no
indication of new parts since 2014 or earlier. As such, deprecate the
driver with the aim of removing it prior to FreeBSD 15.

Reviewed by: emaste
Differential Revision: https://reviews.freebsd.org/D40531

(cherry picked from commit 4591322980a37d6ee38a3ed70569366e16ca71f6)