sched/core: Fix comparison in sched_group_cookie_match()

In commit 97886d9d ("sched: Migration changes for core scheduling"),
sched_group_cookie_match() was added to help determine if a cookie
matches the core state.

However, while it iterates the SMT group, it fails to actually use the
RQ for each of the CPUs iterated, use cpu_rq(cpu) instead of rq to fix
things.

Fixes: 97886d9d

 ("sched: Migration changes for core scheduling")
Signed-off-by: Lin Shengwang <linshengwang1@huawei.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20221008022709.642-1-linshengwang1@huawei.com