selftests/bpf: Add xdp_feature selftest for bond device

Introduce selftests to check xdp_feature support for bond driver.

Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Jussi Maki <joamaki@gmail.com>
Link: https://lore.kernel.org/bpf/64cb8f20e6491f5b971f8d3129335093c359aad7.1684329998.git.lorenzo@kernel.org