GC never enabled support for SIOCGADDRROM and SIOCGCHIPID.

When de(4) was imported in 1997 the world was not ready for these ioctls.
In over 20 years that hasn't changed so it seems safe to assume their
time will never come.

Reviewed by: imp, jhb
Approved by: CheriBSD
MFC after: 1 week
Sponsored by: DARPA, AFRL
Differential Revision: https://reviews.freebsd.org/D14889