pxe_netdev now holds a reference to the network device.
Use generic fields in struct device_description rather than assuming
that the struct device * is contained within a pci_device or
isapnp_device; this assumption is broken when using the undionly
driver.
Add PXENV_UNDI_SET_STATION_ADDRESS.
Updated PXE UDP implementation to use the new Etherboot UDP API.
Updated PXE API dispatcher to use copy_{to,from}_user, and moved to
arch/i386 since the implementation is quite architecture-dependent.
(The individual PXE API calls can be largely
architecture-independent.)