common: Drop linux/bug.h from common header

Move this uncommon header out of the common header.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/fs/yaffs2/yportenv.h b/fs/yaffs2/yportenv.h
index 251eba0..081391a 100644
--- a/fs/yaffs2/yportenv.h
+++ b/fs/yaffs2/yportenv.h
@@ -17,6 +17,7 @@
 #ifndef __YPORTENV_H__
 #define __YPORTENV_H__
 
+#include <linux/bug.h>
 #include <linux/types.h>
 
 /* Definition of types */