net: ethernet: liquidio: remove unused structs

'niclist' and 'oct_link_status_resp' are unused since the original
commit f21fb3ed ("Add support of Cavium Liquidio ethernet
adapters").

Remove them.

Signed-off-by: Dr. David Alan Gilbert <linux@treblig.org>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>