alpha: Use generic show_interrupts()

The only subtle difference is that alpha uses ACTUAL_NR_IRQS and
prints the IRQF_DISABLED flag.

Change the generic implementation to deal with ACTUAL_NR_IRQS if
defined.

The IRQF_DISABLED printing is pointless, as we nowadays run all
interrupts with irqs disabled.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
diff --git a/arch/alpha/Kconfig b/arch/alpha/Kconfig
index cc31bec..bd4160c 100644
--- a/arch/alpha/Kconfig
+++ b/arch/alpha/Kconfig
@@ -11,6 +11,7 @@
 	select HAVE_GENERIC_HARDIRQS
 	select GENERIC_IRQ_PROBE
 	select AUTO_IRQ_AFFINITY if SMP
+	select GENERIC_IRQ_SHOW
 	select GENERIC_HARDIRQS_NO_DEPRECATED
 	help
 	  The Alpha is a 64-bit general-purpose processor designed and