bna: Added flash sub-module and ethtool eeprom entry points.

Change details:
	- The patch adds flash sub-module to the bna driver.
	- Added ethtool set_eeprom() and get_eeprom() entry points to
	  support flash partition read/write operations.

Signed-off-by: Krishna Gudipati <kgudipat@brocade.com>
Signed-off-by: David S. Miller <davem@davemloft.net>