Use net_device_operations structure and netdev_nullify() to allow for
safe dropping of the netdev ref by the driver while other refs still
exist.
Add netdev_irq() method. Net device open()/close() methods should no
longer enable or disable IRQs.
Remove rx_quota; it wasn't used anywhere and added too much complexity
to implementing correct interrupt-masking behaviour in pxe_undi.c.
Add "name" field to struct device to allow human-readable hardware device
names.
Add "dev" pointer in struct net_device to tie network interfaces back to a
hardware device.
Force natural alignment of data types in __table() macros. This seems to
prevent gcc from taking the unilateral decision to occasionally increase
their alignment (which screws up the table packing).