psi: fix compile error for psi cgroupv1 when CONFIG_CGROUP=n

hulk inclusion
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I7OOZR

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

When CONFIG_CGROUP=n ,the compile error is:
In file included from kernel/sched/core.c:13:
kernel/sched/sched.h:2679:22: error: array type has incomplete element type ‘struct cftype’
 extern struct cftype cgroup_v1_psi_files[];
                      ^~~~~~~~~~~~~~~~~~~
the reason is then CONFIG_CGROUP=n, struct cftype is not defined. We
also find that, cgroup_v1_psi_files is used only in
kernel/cgroup/cgroup.c and kernel/sched/cpuacct.c. Therefore, move
extern struct cftype cgroup_v1_psi_files to kernel/sched/cpuacct.c.This
also solved the compile error, because, then CONFIG_CGROUP=n,
CONFIG_CGROUP_CPUACCT=n, the kernel/sched/cpuacct.c is not compiled,
which will solve the compile error.
Signed-off-by: NLu Jialin <lujialin4@huawei.com>
(cherry picked from commit 61413516)

kernel/sched/cpuacct.c

@@ -390,6 +390,7 @@ static int __init setup_psi_v1(char *str)
 }
 __setup("psi_v1=", setup_psi_v1);
 
+extern struct cftype cgroup_v1_psi_files[];
 static int __init cgroup_v1_psi_init(void)
 {
 	if (!psi_v1_enable)

kernel/sched/sched.h

@@ -2950,10 +2950,6 @@ unsigned long scale_irq_capacity(unsigned long util, unsigned long irq, unsigned
 }
 #endif
 
-#ifdef CONFIG_PSI
-extern struct cftype cgroup_v1_psi_files[];
-#endif
-
 #if defined(CONFIG_ENERGY_MODEL) && defined(CONFIG_CPU_FREQ_GOV_SCHEDUTIL)
 
 #define perf_domain_span(pd) (to_cpumask(((pd)->em_pd->cpus)))