netxen: fix tx timeout recovery

o In case of tx timeout, firmare may be healthy, but some pci-func may
  see no response from it. Force firmware reset, if some pci-func
  explicitly requests so.

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