perf kwork: Remove unreachable judgments

When s2[i] = '\0', if s1[i] != '\0', it will be judged by ret,
and if s1[i] = '\0', it will be judegd by !s1[i].
So in reality, s2 [i] will never make a judgment

Signed-off-by: Feng Yang <yangfeng@kylinos.cn>
Reviewed-by: Ian Rogers <irogers@google.com>
Link: https://lore.kernel.org/r/20250314031013.94480-1-yangfeng59949@163.com


Signed-off-by: Namhyung Kim <namhyung@kernel.org>