Merge branch 'netdev-genl-add-an-xsk-attribute-to-queues'

Joe Damato says:

====================
netdev-genl: Add an xsk attribute to queues

This is an attempt to followup on something Jakub asked me about [1],
adding an xsk attribute to queues and more clearly documenting which
queues are linked to NAPIs...

After the RFC [2], Jakub suggested creating an empty nest for queues
which have a pool, so I've adjusted this version to work that way.

The nest can be extended in the future to express attributes about XSK
as needed. Queues which are not used for AF_XDP do not have the xsk
attribute present.

I've run the included test on:
  - my mlx5 machine (via NETIF=)
  - without setting NETIF

And the test seems to pass in both cases.

[1]: https://lore.kernel.org/netdev/20250113143109.60afa59a@kernel.org/
[2]: https://lore.kernel.org/netdev/20250129172431.65773-1-jdamato@fastly.com/
====================

Link: https://patch.msgid.link/20250214211255.14194-1-jdamato@fastly.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>