Clear spurious irq stat information when adding irq handler

Any newly added irq handler may obviously make any old spurious irq
status invalid, since the new handler may well be the thing that is
supposed to handle any interrupts that came in.

So just clear the statistics when adding handlers.
Pointed-out-by: NAlan Cox <alan@lxorguk.ukuu.org.uk>
Acked-by: NThomas Gleixner <tglx@linutronix.de>
Acked-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

kernel/irq/manage.c

@@ -315,6 +315,9 @@ int setup_irq(unsigned int irq, struct irqaction *new)
 			/* Undo nested disables: */
 			desc->depth = 1;
 	}
+	/* Reset broken irq detection when installing new handler */
+	desc->irq_count = 0;
+	desc->irqs_unhandled = 0;
 	spin_unlock_irqrestore(&desc->lock, flags);
 
 	new->irq = irq;