This patch fixes a deadlock which occurs when a PCMCIA card is
physically removed, and the netdev interface is then downed.

The problem occurs because these drivers delay the call of
unregister_netdev until the netdev is downed.

Since 2.6 now downs the interface on unregister_netdev(), we can
call this function as soon as the card has been removed without
waiting for the netdev to be downed.