[S390] irq change improvements.

Remove the last few places where a pointer to pt_regs gets passed.
Also make sure we call set_irq_regs() before irq_enter() and after
irq_exit(). This doesn't fix anything but makes sure s390 looks the
same like all other architectures.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
diff --git a/arch/s390/kernel/s390_ext.c b/arch/s390/kernel/s390_ext.c
index c49ab8c..4faf96f 100644
--- a/arch/s390/kernel/s390_ext.c
+++ b/arch/s390/kernel/s390_ext.c
@@ -117,8 +117,8 @@
         int index;
 	struct pt_regs *old_regs;
 
-	irq_enter();
 	old_regs = set_irq_regs(regs);
+	irq_enter();
 	asm volatile ("mc 0,0");
 	if (S390_lowcore.int_clock >= S390_lowcore.jiffy_timer)
 		/**
@@ -134,8 +134,8 @@
 				p->handler(code);
 		}
 	}
-	set_irq_regs(old_regs);
 	irq_exit();
+	set_irq_regs(old_regs);
 }
 
 EXPORT_SYMBOL(register_external_interrupt);