s390/idle: add missing irq off lockdep annotation

psw_idle() returns with interrupts disabled, so we should add the
missing annotation.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

arch/s390/kernel/idle.c

diff --git a/arch/s390/kernel/idle.c b/arch/s390/kernel/idle.c
index 05fbc2c..8814dd9 100644
--- a/arch/s390/kernel/idle.c
+++ b/arch/s390/kernel/idle.c
@@ -35,6 +35,8 @@
 	/* Call the assembler magic in entry.S */
 	psw_idle(idle, psw_mask);
 
+	trace_hardirqs_off();
+
 	/* Account time spent with enabled wait psw loaded as idle time. */
 	idle->sequence++;
 	smp_wmb();