ice: Remove next_{dd,rs} fields from ice_tx_ring

Now that both ZC and standard XDP data paths stopped using Tx logic
based on next_dd and next_rs fields, we can safely remove these fields
and shrink Tx ring structure.
Signed-off-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Alexander Lobakin <alexandr.lobakin@intel.com>
Link: https://lore.kernel.org/bpf/20230131204506.219292-13-maciej.fijalkowski@intel.com

drivers/net/ethernet/intel/ice/ice_ethtool.c

@@ -3046,8 +3046,6 @@ ice_set_ringparam(struct net_device *netdev, struct ethtool_ringparam *ring,
 		/* clone ring and setup updated count */
 		xdp_rings[i] = *vsi->xdp_rings[i];
 		xdp_rings[i].count = new_tx_cnt;
-		xdp_rings[i].next_dd = ICE_RING_QUARTER(&xdp_rings[i]) - 1;
-		xdp_rings[i].next_rs = ICE_RING_QUARTER(&xdp_rings[i]) - 1;
 		xdp_rings[i].desc = NULL;
 		xdp_rings[i].tx_buf = NULL;
 		err = ice_setup_tx_ring(&xdp_rings[i]);

drivers/net/ethernet/intel/ice/ice_main.c

@@ -2570,8 +2570,6 @@ static int ice_xdp_alloc_setup_rings(struct ice_vsi *vsi)
 		xdp_ring->netdev = NULL;
 		xdp_ring->dev = dev;
 		xdp_ring->count = vsi->num_tx_desc;
-		xdp_ring->next_dd = ICE_RING_QUARTER(xdp_ring) - 1;
-		xdp_ring->next_rs = ICE_RING_QUARTER(xdp_ring) - 1;
 		WRITE_ONCE(vsi->xdp_rings[i], xdp_ring);
 		if (ice_setup_tx_ring(xdp_ring))
 			goto free_xdp_rings;

drivers/net/ethernet/intel/ice/ice_txrx.c

@@ -174,8 +174,6 @@ void ice_clean_tx_ring(struct ice_tx_ring *tx_ring)
 
 	tx_ring->next_to_use = 0;
 	tx_ring->next_to_clean = 0;
-	tx_ring->next_dd = ICE_RING_QUARTER(tx_ring) - 1;
-	tx_ring->next_rs = ICE_RING_QUARTER(tx_ring) - 1;
 
 	if (!tx_ring->netdev)
 		return;

drivers/net/ethernet/intel/ice/ice_txrx.h

@@ -343,8 +343,6 @@ struct ice_tx_ring {
 	struct xsk_buff_pool *xsk_pool;
 	u16 next_to_use;
 	u16 next_to_clean;
-	u16 next_rs;
-	u16 next_dd;
 	u16 q_handle;			/* Queue handle per TC */
 	u16 reg_idx;			/* HW register index of the ring */
 	u16 count;			/* Number of descriptors */