bna: Firmware update

Change Details:
 -      Added Stats clear counter to the bfi_enet_stats_mac structure and
        ethtool stats
 -      Modified the firmware naming convention to contain the firmware image
        version (3.1.0.0). The new convention is
        <firmware-image>-<firmware-version>.bin The change will enforce loading
        only compatible firmware with this driver and also avoid over-writing
        the old firmware image in-order to load new version driver as the
        firmware names used to be the same.

Signed-off-by: Rasesh Mody <rmody@brocade.com>
Signed-off-by: David S. Miller <davem@davemloft.net>