selftests/bpf: Mute xdpxceiver.c's deprecation warnings

xdpxceiver.c is using AF_XDP APIs that are deprecated starting from
libbpf 0.7. Until we migrate the test to libxdp or solve this issue in
some other way, mute deprecation warnings within xdpxceiver.c.

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20211201232824.3166325-6-andrii@kernel.org