Move ALLOC_CACHE_ALIGN_BUFFER() to the new memalign.h header

Now that we have a new header file for cache-aligned allocation, we should
move the stack-based allocation macro there also.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/disk/part_dos.c b/disk/part_dos.c
index cf1a36e..89263d3 100644
--- a/disk/part_dos.c
+++ b/disk/part_dos.c
@@ -17,6 +17,7 @@
 #include <common.h>
 #include <command.h>
 #include <ide.h>
+#include <memalign.h>
 #include "part_dos.h"
 
 #ifdef HAVE_BLOCK_DEVICE