af_xdp: update af_xdp driver plugin to depend on libxdp

af_xdp: update af_xdp driver plugin to depend on libxdp

AF_XDP support is deprecated in libbpf since v0.7.0 [1], the libxdp library
now provides the functionality which once was in libbpf, this commit updates
af_xdp plugin to depend on libxdp, libbpf still remains a dependency even if
libxdp is present, as it need use libbpf APIs for program loading.

libxdp is distributed within xdp-tool [2], xdp-tools package also
include libbpf in it as dependency, so here installed libxdp v1.2.9 and
libbpf v0.8.0, both from xdp-tool-1.2.9 package.

More information about libxdp compatibility can be found in the libxdp
README [3].

In libbpf v0.8.0, The bpf_prog_load function was deprecated and changed to
bpf_object__open_file and bpf_object__next_program and bpf_object__load,
The bpf_get_link_xdp_id and bpf_set_link_xdp_fd functions were deprecated
and changed to bpf_xdp_attach and bpf_xdp_detach, The bpf_object__unload
function was deprecated and changed to bpf_object__close.

[1] https://github.com/libbpf/libbpf/commit/277846bc6c15
[2] https://github.com/xdp-project/xdp-tools/releases/tag/v1.2.9
[3] https://github.com/xdp-project/xdp-tools/blob/master/lib/libxdp/README.org

Type: improvement

Change-Id: Ifbf6e3aa38bc6e0b77561f26311fd11c15ddb47e
Signed-off-by: Yulong Pei <yulong.pei@intel.com>