netxen: fix link speed reporting for some boards

o Read negotiated link speed when link state changes.
o Fix link speed reporting for hybrid nic boards, which have both 1Gbps and
  10Gbps ports.

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