preempt: Move PREEMPT_NEED_RESCHED definition into arch code

PREEMPT_NEED_RESCHED is never used directly, so move it into the arch
code where it can potentially be implemented using either a different
bit in the preempt count or as an entirely separate entity.

Cc: Robert Love <rml@tech9.net>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>

arch/s390/include/asm/preempt.h

@@ -8,6 +8,8 @@
 
 #ifdef CONFIG_HAVE_MARCH_Z196_FEATURES
 
+/* We use the MSB mostly because its available */
+#define PREEMPT_NEED_RESCHED	0x80000000
 #define PREEMPT_ENABLED	(0 + PREEMPT_NEED_RESCHED)
 
 static inline int preempt_count(void)

arch/x86/include/asm/preempt.h

@@ -8,6 +8,9 @@
 
 DECLARE_PER_CPU(int, __preempt_count);
 
+/* We use the MSB mostly because its available */
+#define PREEMPT_NEED_RESCHED	0x80000000
+
 /*
  * We use the PREEMPT_NEED_RESCHED bit as an inverted NEED_RESCHED such
  * that a decrement hitting 0 means we can and should reschedule.

include/linux/preempt.h

@@ -53,9 +53,6 @@
 
 #define SOFTIRQ_DISABLE_OFFSET	(2 * SOFTIRQ_OFFSET)
 
-/* We use the MSB mostly because its available */
-#define PREEMPT_NEED_RESCHED	0x80000000
-
 #define PREEMPT_DISABLED	(PREEMPT_DISABLE_OFFSET + PREEMPT_ENABLED)
 
 /*