alpha: Fix RTC interrupt setup.

Following commit 091738a2 ("genirq: Remove real old transition
functions") we removed an automatic conversion of no_irq_chip to
dummy_irq_chip.  This change needs to be propagated back into the alpha
backend.
Signed-off-by: NRichard Henderson <rth@twiddle.net>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

arch/alpha/kernel/irq_alpha.c

@@ -228,7 +228,7 @@ struct irqaction timer_irqaction = {
 void __init
 init_rtc_irq(void)
 {
-	irq_set_chip_and_handler_name(RTC_IRQ, &no_irq_chip,
+	irq_set_chip_and_handler_name(RTC_IRQ, &dummy_irq_chip,
 				      handle_simple_irq, "RTC");
 	setup_irq(RTC_IRQ, &timer_irqaction);
 }