sh: Decouple 4k and soft/hardirq stacks.

While using separate IRQ stacks can cut down on stack consumption,
many users can also use 4k stacks directly without the additional
need of separate stacks for soft and hardirqs.

With this split, we support the same rationale for 4KSTACKS as
m68knommu, with the IRQSTACKS abstraction as per ppc64.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>
diff --git a/include/asm-sh/irq.h b/include/asm-sh/irq.h
index c61d902..11850f6 100644
--- a/include/asm-sh/irq.h
+++ b/include/asm-sh/irq.h
@@ -41,7 +41,7 @@
 #define irq_canonicalize(irq)	(irq)
 #define irq_demux(irq)		sh_mv.mv_irq_demux(irq)
 
-#ifdef CONFIG_4KSTACKS
+#ifdef CONFIG_IRQSTACKS
 extern void irq_ctx_init(int cpu);
 extern void irq_ctx_exit(int cpu);
 # define __ARCH_HAS_DO_SOFTIRQ