netxen: fix interrupt for NX2031

Signed-off-by: Amit Kumar Salecha <amit.salecha@qlogic.com>

For NX2031, msix is supported from fw version > 3.4.336.
This fw version check should take flash fw in consider instead of
running fw or fw from file.
Signed-off-by: David S. Miller <davem@davemloft.net>