[ARM] Ensure linux/hardirqs.h is included where required

... for the removal of it from asm-generic/local.h

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
diff --git a/arch/arm/kernel/traps.c b/arch/arm/kernel/traps.c
index 57e6874..79abc4d 100644
--- a/arch/arm/kernel/traps.c
+++ b/arch/arm/kernel/traps.c
@@ -18,6 +18,7 @@
 #include <linux/personality.h>
 #include <linux/kallsyms.h>
 #include <linux/delay.h>
+#include <linux/hardirq.h>
 #include <linux/init.h>
 #include <linux/uaccess.h>