psi: make psi_enable static

commit 9289c5e6a78a5a9397df5fa60eb82b105abcfecf upstream.

psi_enable is not used outside of psi.c, make it static.

Link: http://lkml.kernel.org/r/20190319235619.260832-3-surenb@google.comSigned-off-by: NSuren Baghdasaryan <surenb@google.com>
Suggested-by: NAndrew Morton <akpm@linux-foundation.org>
Acked-by: NJohannes Weiner <hannes@cmpxchg.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: NJoseph Qi <joseph.qi@linux.alibaba.com>
Acked-by: NCaspar Zhang <caspar@linux.alibaba.com>

kernel/sched/psi.c

@@ -140,9 +140,9 @@ static int psi_bug __read_mostly;
 DEFINE_STATIC_KEY_FALSE(psi_disabled);
 
 #ifdef CONFIG_PSI_DEFAULT_DISABLED
-bool psi_enable;
+static bool psi_enable;
 #else
-bool psi_enable = true;
+static bool psi_enable = true;
 #endif
 static int __init setup_psi(char *str)
 {