netxen: fix ethtool link test

o Fix ethtool link test for NX3031 chip.
o Remove unused code from phy interrupt callback

Signed-off-by: Sucheta Chakraborty <sucheta.chakraborty@qlogic.com>
Signed-off-by: Amit Kumar Salecha <amit.salecha@qlogic.com>
Signed-off-by: David S. Miller <davem@davemloft.net>