sched/headers: Add header guard to kernel/sched/sched.h

Use the canonical header guard naming of the full path to the header.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Peter Zijlstra <peterz@infradead.org>

kernel/sched/sched.h

@@ -2,6 +2,9 @@
 /*
  * Scheduler internal types and methods:
  */
+#ifndef _KERNEL_SCHED_SCHED_H
+#define _KERNEL_SCHED_SCHED_H
+
 #include <linux/sched.h>
 
 #include <linux/sched/autogroup.h>
@@ -3137,3 +3140,4 @@ extern int sched_dynamic_mode(const char *str);
 extern void sched_dynamic_update(int mode);
 #endif
 
+#endif /* _KERNEL_SCHED_SCHED_H */