selftests: kselftest: Fix the wrong format specifier

The format specifier of "unsigned int" in printf()
should be "%u", not "%d".

Link: https://lore.kernel.org/r/20241202043111.3888-1-zhangjiao2@cmss.chinamobile.com


Signed-off-by: zhang jiao <zhangjiao2@cmss.chinamobile.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>