s390/idle: add missing irq off lockdep annotation

psw_idle() returns with interrupts disabled, so we should add the
missing annotation.
Signed-off-by: NHeiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>

arch/s390/kernel/idle.c

@@ -35,6 +35,8 @@ void enabled_wait(void)
 	/* 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();