genirq: irq_pipeline: fix IRQ state tracing

Since synchronizing the in-band log implies turning interrupts on
(trace_hardirqs_on()), irq_cpuidle_enter() must call
trace_hardirqs_off() conversely when stalling the stage on return.
Signed-off-by: Philippe Gerum <rpm@xenomai.org>

kernel/irq/pipeline.c

@@ -1563,6 +1563,7 @@ bool irq_cpuidle_enter(struct cpuidle_device *dev,
 		unstall_inband_nocheck();
 		synchronize_pipeline();
 		stall_inband_nocheck();
+		trace_hardirqs_off();
 		return false;
 	}