sched: fix the cpuprio count really

Peter pointed out that the last version of the "fix" was still one off
under certain circumstances. Use BITS_TO_LONG instead to get an
accurate result.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

kernel/sched_cpupri.h

@@ -3,8 +3,8 @@
 
 #include <linux/sched.h>
 
-#define CPUPRI_NR_PRIORITIES 2+MAX_RT_PRIO
-#define CPUPRI_NR_PRI_WORDS (CPUPRI_NR_PRIORITIES + BITS_PER_LONG/2)/BITS_PER_LONG
+#define CPUPRI_NR_PRIORITIES	(MAX_RT_PRIO + 2)
+#define CPUPRI_NR_PRI_WORDS	BITS_TO_LONGS(CPUPRI_NR_PRIORITIES)
 
 #define CPUPRI_INVALID -1
 #define CPUPRI_IDLE     0