netxen: fix physical port mapping

The PCI function to physical port mapping is valid only for
old firmware. New firmware (4.0.0+) abstracts this.
So driver should never try to access phy using invalid
mapping. The behavior is unpredictable when PCI functions
4-7 are enabled on the same NIC.

Signed-off-by: Dhananjay Phadke <dhananjay@netxen.com>
Signed-off-by: David S. Miller <davem@davemloft.net>