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/fs/fat/fat.c b/fs/fat/fat.c
index a863644..06dcbb7 100644
--- a/fs/fat/fat.c
+++ b/fs/fat/fat.c
@@ -16,6 +16,7 @@
 #include <asm/byteorder.h>
 #include <part.h>
 #include <malloc.h>
+#include <memalign.h>
 #include <linux/compiler.h>
 #include <linux/ctype.h>