selftests/xsk: Introduce set_ring_size function with a retry mechanism for handling...

selftests/xsk: Introduce set_ring_size function with a retry mechanism for handling AF_XDP socket closures

Introduce a new function, set_ring_size(), to manage asynchronous AF_XDP
socket closure. Retry set_hw_ring_size up to SOCK_RECONF_CTR times if it
fails due to an active AF_XDP socket. Return an error immediately for
non-EBUSY errors. This enhances robustness against asynchronous AF_XDP
socket closures during ring size changes.

Signed-off-by: Tushar Vyavahare <tushar.vyavahare@intel.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Magnus Karlsson <magnus.karlsson@intel.com>
Link: https://lore.kernel.org/bpf/20240402114529.545475-6-tushar.vyavahare@intel.com