selftests/bpf: Correct two typos

When wrapping code, use ';' better than using ',' which is more in line with
the coding habits of most engineers.

Signed-off-by: Lu Hongfei <luhongfei@vivo.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Hou Tao <houtao1@huawei.com>
Acked-by: Stanislav Fomichev <sdf@google.com>
Link: https://lore.kernel.org/bpf/20230707081253.34638-1-luhongfei@vivo.com