ARM: 6197/2: preliminary support for sparse IRQ

So to allow NR_IRQS to be dynamic and platforms to specify the number
of IRQs really needed.

Acked-by: Paul Mundt <lethal@linux-sh.org>
Signed-off-by: Eric Miao <eric.y.miao@gmail.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
diff --git a/arch/arm/include/asm/irq.h b/arch/arm/include/asm/irq.h
index 237282f..2721a58 100644
--- a/arch/arm/include/asm/irq.h
+++ b/arch/arm/include/asm/irq.h
@@ -7,6 +7,8 @@
 #define irq_canonicalize(i)	(i)
 #endif
 
+#define NR_IRQS_LEGACY	16
+
 /*
  * Use this value to indicate lack of interrupt
  * capability