tools/bpf: Remove unused variable from runqslower

This variable is never referenced in the code, just remove it.

Signed-off-by: Zhu Jun <zhujun2@cmss.chinamobile.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20240925100005.3989-1-zhujun2@cmss.chinamobile.com


Signed-off-by: Alexei Starovoitov <ast@kernel.org>