net/i40e: fix flow director Rx writeback packet

net/i40e: fix flow director Rx writeback packet

This patch fixes the fdir cannot receive rx writeback packet issue.
The root cause is FDIR interrupt is not correctly enabled.

Beside this, to make sure fdir programming works fine when the port
is stopped, move the fdir interrupt configure from start/stop to
setup/teardown.

Fixes: cfd662d22e7b ("net/i40e: fix interrupt throttling setting in PF")
Cc: stable@dpdk.org
Signed-off-by: Chenmin Sun <chenmin.sun@intel.com>
Acked-by: Beilei Xing <beilei.xing@intel.com>