sched/topology: Remove unused numa_distance in cpu_attach_domain()

numa_distance in cpu_attach_domain() is introduced in
commit b5b2173 ("sched/topology: Warn when NUMA diameter > 2")
to warn user when NUMA diameter > 2 as we'll misrepresent
the scheduler topology structures at that time. This is
fixed by Barry in commit 585b6d2 ("sched/topology: fix the issue
groups don't span domain->span for NUMA diameter > 2") and
numa_distance is unused now. So remove it.

Signed-off-by: Yicong Yang <yangyicong@hisilicon.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Barry Song <baohua@kernel.org>
Reviewed-by: Valentin Schneider <valentin.schneider@arm.com>
Link: https://lore.kernel.org/r/20210915063158.80639-1-yangyicong@hisilicon.com

kernel/sched/topology.c

@@ -688,7 +688,6 @@ cpu_attach_domain(struct sched_domain *sd, struct root_domain *rd, int cpu)
 {
 	struct rq *rq = cpu_rq(cpu);
 	struct sched_domain *tmp;
-	int numa_distance = 0;
 
 	/* Remove the sched domains which do not contribute to scheduling. */
 	for (tmp = sd; tmp; ) {
@@ -732,9 +731,6 @@ cpu_attach_domain(struct sched_domain *sd, struct root_domain *rd, int cpu)
 		}
 	}
 
-	for (tmp = sd; tmp; tmp = tmp->parent)
-		numa_distance += !!(tmp->flags & SD_NUMA);
-
 	sched_domain_debug(sd, cpu);
 
 	rq_attach_root(rq, rd);