selftests/bpf: Remove second semicolon

There are statements with two semicolons. Remove the second one, it
is redundant.

Signed-off-by: Colin Ian King <colin.i.king@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20240315092654.2431062-1-colin.i.king@gmail.com