igb: Introduce XSK data structures and helpers

Add the following ring flag:
- IGB_RING_FLAG_TX_DISABLED (when xsk pool is being setup)

Add a xdp_buff array for use with XSK receive batch API, and a pointer
to xsk_pool in igb_adapter.

Add enable/disable functions for TX and RX rings.
Add enable/disable functions for XSK pool.
Add xsk wakeup function.

None of the above functionality will be active until
NETDEV_XDP_ACT_XSK_ZEROCOPY is advertised in netdev->xdp_features.

Signed-off-by: Sriram Yagnaraman <sriram.yagnaraman@est.tech>
[Kurt: Add READ/WRITE_ONCE(), synchronize_net(),
       remove IGB_RING_FLAG_AF_XDP_ZC]
Signed-off-by: Kurt Kanzenbach <kurt@linutronix.de>
Reviewed-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
Tested-by: George Kuruvinakunnel <george.kuruvinakunnel@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>
Link: https://patch.msgid.link/20250106221929.956999-4-anthony.l.nguyen@intel.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>