Fix copyright header

Reviewed-by: Richard Levitte <levitte@openssl.org>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
(Merged from #20473)

crypto/bn/rsa_sup_mul.c

@@ -1,3 +1,12 @@
+/*
+ * Copyright 2022-2023 The OpenSSL Project Authors. All Rights Reserved.
+ *
+ * Licensed under the OpenSSL license (the "License").  You may not use
+ * this file except in compliance with the License.  You can obtain a copy
+ * in the file LICENSE in the source distribution or at
+ * https://www.openssl.org/source/license.html
+ */
+
 #include <openssl/e_os2.h>
 #include <stddef.h>
 #include <sys/types.h>