selftests/bpf: Add drv mode testing for xdping

As subject, we only test SKB mode for xdping at present.
Now add DRV mode for xdping.

Signed-off-by: Hangbin Liu <liuhangbin@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Song Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/20220602032507.464453-1-liuhangbin@gmail.com