[ARM] 5359/1: Kirkwood: fix compilation error

Commit ba84be23 broke the build.
Signed-off-by: Nicolas Pitre <nico@marvell.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

arch/arm/mach-kirkwood/pcie.c

@@ -11,6 +11,7 @@
 #include <linux/kernel.h>
 #include <linux/pci.h>
 #include <linux/mbus.h>
+#include <asm/irq.h>
 #include <asm/mach/pci.h>
 #include <plat/pcie.h>
 #include "common.h"