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/drivers/usb/eth/asix.c b/drivers/usb/eth/asix.c
index 8a43e7c..ad083cf 100644
--- a/drivers/usb/eth/asix.c
+++ b/drivers/usb/eth/asix.c
@@ -10,6 +10,7 @@
 #include <dm.h>
 #include <usb.h>
 #include <malloc.h>
+#include <memalign.h>
 #include <linux/mii.h>
 #include "usb_ether.h"