crypto: Fix dead links

Signed-off-by: Adrian-Ken Rueegsegger <ken@codelabs.ch>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
diff --git a/crypto/sha256_generic.c b/crypto/sha256_generic.c
index caa3542..6349d83 100644
--- a/crypto/sha256_generic.c
+++ b/crypto/sha256_generic.c
@@ -2,7 +2,7 @@
  * Cryptographic API.
  *
  * SHA-256, as specified in
- * http://csrc.nist.gov/cryptval/shs/sha256-384-512.pdf
+ * http://csrc.nist.gov/groups/STM/cavp/documents/shs/sha256-384-512.pdf
  *
  * SHA-256 code by Jean-Luc Cooke <jlcooke@certainkey.com>.
  *