Move from memcpy to memcpy_s.

Change-Id: If7d53c6e54428f01f14528c3f281331d308af56a
diff --git a/src/api.c b/src/api.c
index ec98c22..a726404 100644
--- a/src/api.c
+++ b/src/api.c
@@ -809,7 +809,8 @@
 	/* Copy data. */
 	to_msg = to->mailbox.recv;
 	*to_msg = from_msg_replica;
-	memcpy(to_msg->payload, from->mailbox.send->payload, size);
+	memcpy_s(to_msg->payload, SPCI_MSG_PAYLOAD_MAX,
+		 from->mailbox.send->payload, size);
 	primary_ret.message.vm_id = to->id;
 	ret = SPCI_SUCCESS;