crypto: blake2b - update file comment

The file comment for blake2b_generic.c makes it sound like it's the
reference implementation of BLAKE2b with only minor changes.  But it's
actually been changed a lot.  Update the comment to make this clearer.
Reviewed-by: David Sterba <dsterba@suse.com>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

crypto/blake2b_generic.c

 // SPDX-License-Identifier: (GPL-2.0-only OR Apache-2.0)
 /*
- * BLAKE2b reference source code package - reference C implementations
+ * Generic implementation of the BLAKE2b digest algorithm.  Based on the BLAKE2b
+ * reference implementation, but it has been heavily modified for use in the
+ * kernel.  The reference implementation was:
  *
- * Copyright 2012, Samuel Neves <sneves@dei.uc.pt>.  You may use this under the
- * terms of the CC0, the OpenSSL Licence, or the Apache Public License 2.0, at
- * your option.  The terms of these licenses can be found at:
+ *	Copyright 2012, Samuel Neves <sneves@dei.uc.pt>.  You may use this under
+ *	the terms of the CC0, the OpenSSL Licence, or the Apache Public License
+ *	2.0, at your option.  The terms of these licenses can be found at:
  *
  *	- CC0 1.0 Universal : http://creativecommons.org/publicdomain/zero/1.0
  *	- OpenSSL license   : https://www.openssl.org/source/license.html
  *	- Apache 2.0        : https://www.apache.org/licenses/LICENSE-2.0
  *
- * More information about the BLAKE2 hash function can be found at
- * https://blake2.net.
- *
- * Note: the original sources have been modified for inclusion in linux kernel
- * in terms of coding style, using generic helpers and simplifications of error
- * handling.
+ * More information about BLAKE2 can be found at https://blake2.net.
  */
 
 #include <asm/unaligned.h>