microblaze: remove duplicated #include

Remove duplicated #include('s) in
  arch/microblaze/include/asm/io.h

Signed-off-by: Huang Weiyi <weiyi.huang@gmail.com>
Signed-off-by: Michal Simek <monstr@monstr.eu>

arch/microblaze/include/asm/io.h

@@ -14,7 +14,6 @@
 #include <asm/byteorder.h>
 #include <asm/page.h>
 #include <linux/types.h>
-#include <asm/byteorder.h>
 #include <linux/mm.h>          /* Get struct page {...} */