netxen: support for GbE port settings

o Enable setting speed and auto negotiation parameters for GbE ports.
o Hardware do not support half duplex setting currently.

David Miller:
	Amit please update your patch to silently reject link setting
	attempts that are unsupported by the device.

Signed-off-by: Sony Chacko <sony.chacko@qlogic.com>
Signed-off-by: Amit Kumar Salecha <amit.salecha@qlogic.com>
Signed-off-by: David S. Miller <davem@davemloft.net>