[PATCH] netdev: don't allow register_netdev with blank name

This bit of old backwards compatibility cruft can be removed in 2.6.20.
If there is still an device that calls register_netdev()
with a zero or blank name, it will get -EINVAL from register_netdevice().

Signed-off-by: Stephen Hemminger <shemminger@osdl.org>
Signed-off-by: Jeff Garzik <jeff@garzik.org>