idpf: add support for XDP on Rx

idpf: add support for XDP on Rx

Use libeth XDP infra to support running XDP program on Rx polling.
This includes all of the possible verdicts/actions.
XDP Tx queues are cleaned only in "lazy" mode when there are less than
1/4 free descriptors left on the ring. libeth helper macros to define
driver-specific XDP functions make sure the compiler could uninline
them when needed.

Use __LIBETH_WORD_ACCESS to parse descriptors more efficiently when
applicable. It really gives some good boosts and code size reduction
on x86_64:

XDP only: add/remove: 0/0 grow/shrink: 3/3 up/down: 5/-59 (-54)
with XSk: add/remove: 0/0 grow/shrink: 5/6 up/down: 23/-124 (-101)

with the most demanding workloads like XSk xmit differing in up to 5-8%.

Co-developed-by: Michal Kubiak <michal.kubiak@intel.com>
Signed-off-by: Michal Kubiak <michal.kubiak@intel.com>
Signed-off-by: Alexander Lobakin <aleksander.lobakin@intel.com>
Tested-by: Ramu R <ramu.r@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>