ixgbe: Make use of the default fdb handlers.

For fdb_add, use the default handler in the non-SRIOV case.
For the other fdb handlers, just remove them and use the
default ones.

CC: John Fastabend <john.r.fastabend@intel.com>
Acked-By: John Fastabend <john.r.fastabend@intel.com>
CC: CC: Gregory Rose <gregory.v.rose@intel.com>
Signed-off-by: Vlad Yasevich <vyasevic@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>