replaced threads/mp.h includes with threads/cpu.h

This was missing from the previous MPP removal patch

src/tests/threads/balance-synch1.c

@@ -12,8 +12,8 @@
 #include "threads/thread.h"
 #include <debug.h>
 #include "threads/synch.h"
+#include "threads/cpu.h"
 #include <stdio.h>
-#include "threads/mp.h"
 #include "devices/timer.h"
 #include "threads/malloc.h"
 

src/tests/threads/balance.c

@@ -9,8 +9,8 @@
 #include "threads/thread.h"
 #include <debug.h>
 #include "threads/synch.h"
+#include "threads/cpu.h"
 #include <stdio.h>
-#include "threads/mp.h"
 #include "devices/timer.h"
 #include "threads/malloc.h"
 

src/tests/threads/cfs-run-batch.c

@@ -7,7 +7,6 @@
 #include <debug.h>
 #include "threads/synch.h"
 #include <stdio.h>
-#include "threads/mp.h"
 #include "lib/atomic-ops.h"
 
 #define N 30