sched: proper prototype for kernel/sched.c:migration_init()

This patch adds a proper prototype for migration_init() in
include/linux/sched.h

Since there's no point in always returning 0 to a caller that doesn't check
the return value it also changes the function to return void.

Signed-off-by: Adrian Bunk <bunk@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

include/linux/sched.h

@@ -1988,6 +1988,14 @@ static inline void inc_syscw(struct task_struct *tsk)
 }
 #endif
 
+#ifdef CONFIG_SMP
+void migration_init(void);
+#else
+static inline void migration_init(void)
+{
+}
+#endif
+
 #endif /* __KERNEL__ */
 
 #endif