[ARM] 3494/1: asm-arm/bug.h needs linux/stddef.h

Patch from Nicolas Pitre

... for the definition of NULL.
Signed-off-by: Nicolas Pitre <nico@cam.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

include/asm-arm/bug.h

@@ -2,6 +2,7 @@
 #define _ASMARM_BUG_H
 
 #include <linux/config.h>
+#include <linux/stddef.h>
 
 #ifdef CONFIG_BUG
 #ifdef CONFIG_DEBUG_BUGVERBOSE