ixgbe: split XDP_TX tail and XDP_REDIRECT map flushing

The driver was combining the XDP_TX tail flush and XDP_REDIRECT
map flushing (xdp_do_flush_map).  This is suboptimal, these two
flush operations should be kept separate.

Fixes: 11393cc9

 ("xdp: Add batching support to redirect map")
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>