sh: Add support for 4K stacks.

This enables support for 4K stacks on SH.

Currently this depends on DEBUG_KERNEL, but likely all boards
will switch to this as the default in the future.

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

arch/sh/kernel/cpu/irq/ipr.c

@@ -190,6 +190,8 @@ void __init init_IRQ(void)
 	/* Perform the machine specific initialisation */
 	if (sh_mv.mv_init_irq != NULL)
 		sh_mv.mv_init_irq();
+
+	irq_ctx_init(smp_processor_id());
 }
 
 #if !defined(CONFIG_CPU_HAS_PINT_IRQ)