net: ethernet: starfire: remove unused structs

'short_rx_done_desc' and 'basic_rx_done_desc' are unused since
commit fdecea66 ("  [netdrvr starfire] Add GPL'd firmware, remove
compat code").

Remove them.

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