board: boundary: Remove <common.h> and add needed includes

Remove <common.h> from this board vendor directory and when needed
add missing include files directly.

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/board/boundary/nitrogen6x/nitrogen6x.c b/board/boundary/nitrogen6x/nitrogen6x.c
index 382c01d..2b0cb23 100644
--- a/board/boundary/nitrogen6x/nitrogen6x.c
+++ b/board/boundary/nitrogen6x/nitrogen6x.c
@@ -4,7 +4,6 @@
  * Copyright (C) 2013, Boundary Devices <info@boundarydevices.com>
  */
 
-#include <common.h>
 #include <command.h>
 #include <env.h>
 #include <init.h>