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

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

Reviewed-by: Heiko Schocher <hs@denx.de>
Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/board/siemens/iot2050/board.c b/board/siemens/iot2050/board.c
index 0b0686e..ed292c3 100644
--- a/board/siemens/iot2050/board.c
+++ b/board/siemens/iot2050/board.c
@@ -8,7 +8,7 @@
  *   Jan Kiszka <jan.kiszka@siemens.com>
  */
 
-#include <common.h>
+#include <config.h>
 #include <bootstage.h>
 #include <dm.h>
 #include <fdt_support.h>