scx: Fix local DSQ comparison in dispatch_to_local_dsq()

@Gabant noticed in #218 that our
comparison is backwards in dispatch_to_local_dsq() when determining if the
destination rq in a local dispatch is idle. This could cause us to fail to send
resched IPIs to those remote DSQs when a scheduler uses SCX_DSQ_LOCAL_ON when
dispatching. Thankfully, the issue doesn't happen if dispatching to a local DSQ
from the ops.select_cpu() path, as a resched IPI is sent by the core scheduler
if a task is migrated to an idle core on the wakeup path.

Let's fix it.

Reported-by: @Gabant
Signed-off-by: David Vernet <[email protected]>

kernel/sched/ext.c

@@ -2402,7 +2402,7 @@ dispatch_to_local_dsq(struct rq *rq, struct rq_flags *rf, u64 dsq_id,
 		}
 
 		/* if the destination CPU is idle, wake it up */
-		if (dsp && p->sched_class > dst_rq->curr->sched_class)
+		if (dsp && p->sched_class < dst_rq->curr->sched_class)
 			resched_curr(dst_rq);
 
 		dispatch_to_local_dsq_unlock(rq, rf, src_rq, locked_dst_rq);