i40e: add tracking of AF_XDP ZC state for each queue pair

In commit f3fef2b6e1 ("i40e: Remove umem from VSI") a regression was
introduced; When the VSI was reset, the setup code would try to enable
AF_XDP ZC unconditionally (as long as there was a umem placed in the
netdev._rx struct). Here, we add a bitmap to the VSI that tracks if a
certain queue pair has been "zero-copy enabled" via the ndo_bpf. The
bitmap is used in i40e_xsk_umem, and enables zero-copy if and only if
XDP is enabled, the corresponding qid in the bitmap is set and the
umem is non-NULL.

Fixes: f3fef2b6e1 ("i40e: Remove umem from VSI")
Signed-off-by: Björn Töpel <bjorn.topel@intel.com>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

drivers/net/ethernet/intel/i40e/i40e.h

@@ -790,6 +790,8 @@ struct i40e_vsi {
 
 	/* VSI specific handlers */
 	irqreturn_t (*irq_handler)(int irq, void *data);
+
+	unsigned long *af_xdp_zc_qps; /* tracks AF_XDP ZC enabled qps */
 } ____cacheline_internodealigned_in_smp;
 
 struct i40e_netdev_priv {