sh: Kill off now unused arch_probe_nr_irqs().

Now that legacy pre-allocation is done away with, we can just use the
generic stub in kernel/softirq.c.
Signed-off-by: Paul Mundt <lethal@linux-sh.org>

arch/sh/kernel/irq.c

@@ -231,16 +231,6 @@ void __init init_IRQ(void)
 	irq_ctx_init(smp_processor_id());
 }
 
-#ifdef CONFIG_SPARSE_IRQ
-int __init arch_probe_nr_irqs(void)
-{
-	/*
-	 * No pre-allocated IRQs.
-	 */
-	return 0;
-}
-#endif
-
 #ifdef CONFIG_HOTPLUG_CPU
 static void route_irq(struct irq_data *data, unsigned int irq, unsigned int cpu)
 {