arm64/mpam: decrease dom_num when domain goes offline

hulk inclusion
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I61CPK
CVE: NA

--------------------------------

mpam_resctrl_setup_domain() increase dom_num when domain goes online. As
a result, mpam_resctrl_cpu_offline() should decrease dom_num when domain
goes offline.
Signed-off-by: NWang ShaoBo <bobo.shaobowang@huawei.com>
Signed-off-by: NJialin Zhang <zhangjialin11@huawei.com>
Reviewed-by: NXie XiuQi <xiexiuqi@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

arch/arm64/kernel/mpam/mpam_setup.c

@@ -172,6 +172,8 @@ int mpam_resctrl_cpu_offline(unsigned int cpu)
 		list_del(&d->list);
 		dom = container_of(d, struct mpam_resctrl_dom, resctrl_dom);
 		kfree(dom);
+
+		res->resctrl_res.dom_num--;
 	}
 
 	mpam_resctrl_clear_default_cpu(cpu);