We originally were using a per-interface xdp_prog variable to track
a loaded XDP program since we knew there would never be support for a
per-queue XDP program.  With that, we only built the per queue rxq_info
struct when an XDP program was loaded and removed it on XDP program unload,
and used the pointer as an indicator in the Rx hotpath to know to how build
the buffers.  However, that's really not the model generally used, and
makes a conversion to page_pool Rx buffer cacheing a little problematic.

This patch converts the driver to use the more common approach of using
a per-queue xdp_prog pointer to work out buffer allocations and need
for bpf_prog_run_xdp().  We jostle a couple of fields in the queue struct
in order to keep the new xdp_prog pointer in a warm cacheline.
Signed-off-by: Shannon Nelson <shannon.nelson@amd.com>
Signed-off-by: Brett Creeley <brett.creeley@amd.com>
Link: https://patch.msgid.link/20240906232623.39651-4-brett.creeley@amd.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>