Merge branch 'xsk-the-lost-bits-from-chapter-iii'

Alexander Lobakin says:

====================
xsk: the lost bits from Chapter III

Before introducing libeth_xdp, we need to add a couple more generic
helpers. Notably:

* 01: add generic loop unrolling hint helpers;
* 04: add helper to get both xdp_desc's DMA address and metadata
  pointer in one go, saving several cycles and hotpath object
  code size in drivers (especially when unrolling).

Bonus:

* 02, 03: convert two drivers which were using custom macros to
  generic unrolled_count() (trivial, no object code changes).
====================

Link: https://patch.msgid.link/20250206182630.3914318-1-aleksander.lobakin@intel.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>