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/board/samsung/common/misc.c b/board/samsung/common/misc.c
index f0d69d4..e0e2c48 100644
--- a/board/samsung/common/misc.c
+++ b/board/samsung/common/misc.c
@@ -12,6 +12,7 @@
 #include <errno.h>
 #include <version.h>
 #include <malloc.h>
+#include <memalign.h>
 #include <linux/sizes.h>
 #include <asm/arch/cpu.h>
 #include <asm/gpio.h>