NetXen: Use multiple PCI functions

NetXen: Make driver use multiple PCI functions.
This patch will make NetXen driver work with multiple PCI functions. This will
make the usage of memory resources as well as interrupts more independent
among different functions which results in better throughput. This change has
been done after the multiport support is added in firmware.

Signed-off by: Mithlesh Thukral <mithlesh@netxen.com>

Signed-off-by: Jeff Garzik <jeff@garzik.org>