ddr: Remove <common.h> and add needed includes

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

Signed-off-by: Tom Rini <trini@konsulko.com>

drivers/ddr/altera/sequencer.c

@@ -3,8 +3,8 @@
  * Copyright Altera Corporation (C) 2012-2015
  */
 
-#include <common.h>
 #include <log.h>
+#include <linux/string.h>
 #include <asm/io.h>
 #include <asm/arch/sdram.h>
 #include <errno.h>