loongarch_pmu_alloc_counter
idx = loongarch_pmu_alloc_counter(cpuc, hwc);
loongarch_pmu_alloc_counter(&fake_cpuc, &leader->hw) < 0)
loongarch_pmu_alloc_counter(&fake_cpuc, &sibling->hw) < 0)
loongarch_pmu_alloc_counter(&fake_cpuc, &event->hw) < 0)