Blackfin arch: move ack_bad_irq() prototype to hardirq.h to match other arches

Signed-off-by: Mike Frysinger <vapier.adi@gmail.com>
Signed-off-by: Bryan Wu <cooloney@kernel.org>

diff --git a/arch/blackfin/include/asm/hardirq.h b/arch/blackfin/include/asm/hardirq.h
index b6b19f1..717181a 100644
--- a/arch/blackfin/include/asm/hardirq.h
+++ b/arch/blackfin/include/asm/hardirq.h
@@ -42,4 +42,6 @@
 
 #define __ARCH_IRQ_EXIT_IRQS_DISABLED	1
 
+extern void ack_bad_irq(unsigned int irq);
+
 #endif