selftests/bpf: Move summary line after the error logs

Makes it easier to find the summary line when there is a lot of logs to
scroll back.

Signed-off-by: Yucong Sun <sunyucong@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20211112192535.898352-2-fallentree@fb.com