[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/drivers/s390/cio/cio.c b/drivers/s390/cio/cio.c
index f18b162..8936e46 100644
--- a/drivers/s390/cio/cio.c
+++ b/drivers/s390/cio/cio.c
@@ -609,8 +609,8 @@
 	struct irb *irb;
 	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)
 		/**
@@ -655,8 +655,8 @@
 		 * out of the sie which costs more cycles than it saves.
 		 */
 	} while (!MACHINE_IS_VM && tpi (NULL) != 0);
+	irq_exit();
 	set_irq_regs(old_regs);
-	irq_exit ();
 }
 
 #ifdef CONFIG_CCW_CONSOLE