netxen: refactor firmware info code

o Combine netxen_get_firmware_info(), netxen_check_options()
  so that they are updated every time firmware is reset.
o Set dma mask everytime firmware is reset.

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