The recvfrom() syscall is only supported by AF_XDP sockets since
kernel 5.11. Only use it if busy polling is configured. We can
assume a kernel >= 5.11 is in use if busy polling is configured
so we can safely call recvfrom() in that case.
Fixes: 63e8989fe5 ("net/af_xdp: use recvfrom instead of poll syscall")
Signed-off-by: Ciara Loftus <ciara.loftus@intel.com>