The original FDB code submission wasn't correct and the code
wasn't enabled.  This removes some dead code (can use the common kernel
code for fdb_del and fdb_dump) and correctly enables the fdb_add
function pointer.

The fdb_add functionality is important to i40e because it is needed
for a workaround to allow bridges to work correctly on the i40e
hardware.
Reported-by: NJiri Pirko <jiri@resnulli.us>
Signed-off-by: NJesse Brandeburg <jesse.brandeburg@intel.com>
Acked-by: NGreg Rose <gregory.v.rose@intel.com>
Signed-off-by: NJeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: NJiri Pirko <jiri@resnulli.us>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>