arm: Don't include common.h in header files

It is bad practice to include common.h in other header files since it can
bring in any number of superfluous definitions. It implies that some C
files don't include it and thus may be missing CONFIG options that are set
up by that file. The C files should include these themselves.

Update some header files in arch/arm to drop this.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/board/grinn/liteboard/board.c b/board/grinn/liteboard/board.c
index 5d71b63..df32e12 100644
--- a/board/grinn/liteboard/board.c
+++ b/board/grinn/liteboard/board.c
@@ -4,6 +4,7 @@
  * Copyright (C) 2016 Grinn
  */
 
+#include <common.h>
 #include <command.h>
 #include <init.h>
 #include <asm/arch/clock.h>