bpf, tests: Fix typos in comments

Currently, there are two comments with same name "64-bit ATOMIC magnitudes",
the second one should be "32-bit ATOMIC magnitudes" based on the context.

Signed-off-by: Chen Pei <cp0613@linux.alibaba.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/bpf/20240415081928.17440-1-cp0613@linux.alibaba.com