selftests/xsk: Enhance batch size support with dynamic configurations

Introduce dynamic adjustment capabilities for fill_size and comp_size
parameters to support larger batch sizes beyond the previous 2K limit.

Update HW_SW_MAX_RING_SIZE test cases to evaluate AF_XDP's robustness by
pushing hardware and software ring sizes to their limits. This test
ensures AF_XDP's reliability amidst potential producer/consumer throttling
due to maximum ring utilization.

Signed-off-by: Tushar Vyavahare <tushar.vyavahare@intel.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
Link: https://lore.kernel.org/bpf/20240702055916.48071-3-tushar.vyavahare@intel.com