s390/cio: fix irq statistics

When we fetch an interrupt on the CCW console using tsch (via
ccw_device_wait_idle formerly known as wait_cons_dev) we increment
the irq count for the affected interruption class but it is not
accounted as an IO interrupt.

This is broken since commit b603d258a43b4e7339660bdd3b5c25eacd603e54
"s390: remove superfluous tpi from wait_cons_dev"

Fix it so that the sum of the individual interrupts per class matches
the number of IO interrupts again.

Reported-by: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Signed-off-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

drivers/s390/cio/cio.c

@@ -647,6 +647,7 @@ void cio_tsch(struct subchannel *sch)
 		local_bh_disable();
 		irq_enter();
 	}
+	kstat_incr_irqs_this_cpu(IO_INTERRUPT, NULL);
 	if (sch->driver && sch->driver->irq)
 		sch->driver->irq(sch);
 	else