Make LMOTS a private api

Signed-off-by: Raef Coles <raef.coles@arm.com>
diff --git a/library/lms.c b/library/lms.c
index e1ac7b9..d8969ba 100644
--- a/library/lms.c
+++ b/library/lms.c
@@ -36,8 +36,9 @@
 
 #include <string.h>
 
+#include "lmots.h"
+
 #include "mbedtls/lms.h"
-#include "mbedtls/lmots.h"
 #include "mbedtls/md.h"
 #include "mbedtls/error.h"
 #include "mbedtls/platform_util.h"