net: ethernet: 8390: ne2k-pci: remove unused struct 'ne2k_pci_card'

'ne2k_pci_card' is unused since 2.3.99-pre3 in March 2000.

Remove it.

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