m32r: Use preempt_schedule_irq

Use the proper core function instead of fiddling with preempt_active
and interrupt enable in the low level code.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Hirokazu Takata <takata@linux-m32r.org>
Cc: linux-m32r-ja@ml.linux-m32r.org
Link: http://lkml.kernel.org/r/20130917183628.758421136@linutronix.de

arch/m32r/kernel/entry.S

@@ -182,13 +182,7 @@ need_resched:
 	ld	r4, PSW(sp)		; interrupts off (exception path) ?
 	and3	r4, r4, #0x4000
 	beqz	r4, restore_all
-	LDIMM	(r4, PREEMPT_ACTIVE)
-	st	r4, @(TI_PRE_COUNT, r8)
-	ENABLE_INTERRUPTS(r4)
-	bl	schedule
-	ldi	r4, #0
-	st	r4, @(TI_PRE_COUNT, r8)
-	DISABLE_INTERRUPTS(r4)
+	bl	preempt_schedule_irq
 	bra	need_resched
 #endif