netxen: remove unnecessary size checks

NX3031 have 64bit on card memory. Fix the limit check to
64MB and remove unnecessary 128bit read/write check.

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>