sh: Kill off machvec IRQ hinting.

Everything is using sparseirq these days, so we have no need to
arbitrarily size nr_irqs ahead of time. The legacy IRQ pre-allocation
likewise has no meaning for us, so that's killed off too. We now depend
on nr_irqs expansion by the generic hardirq layer instead.

It's also worth noting that the majority of boards had completely bogus
values for their nr_irqs relative to their CPU and configurations, so
this ends up correcting behaviour for quite a few platforms.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>

arch/sh/kernel/irq.c

@@ -234,8 +234,10 @@ void __init init_IRQ(void)
 #ifdef CONFIG_SPARSE_IRQ
 int __init arch_probe_nr_irqs(void)
 {
-	nr_irqs = sh_mv.mv_nr_irqs;
-	return NR_IRQS_LEGACY;
+	/*
+	 * No pre-allocated IRQs.
+	 */
+	return 0;
 }
 #endif