crypto/internal/fips140/sha3: remove outdated TODO

Change-Id: I6a6a6964725fed48b55ce72a24a8f9bd3044ae16
Reviewed-on: https://go-review.googlesource.com/c/go/+/719940
Reviewed-by: Roland Shoemaker <roland@golang.org>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Auto-Submit: Filippo Valsorda <filippo@golang.org>
Reviewed-by: Daniel McCarney <daniel@binaryparadox.net>
Reviewed-by: Junyang Shao <shaojunyang@google.com>

Author: FiloSottile

src/crypto/internal/fips140/sha3/hashes.go

@@ -24,13 +24,6 @@ func New512() *Digest {
 	return &Digest{rate: rateK1024, outputLen: 64, dsbyte: dsbyteSHA3}
 }
 
-// TODO(fips): do this in the stdlib crypto/sha3 package.
-//
-//     crypto.RegisterHash(crypto.SHA3_224, New224)
-//     crypto.RegisterHash(crypto.SHA3_256, New256)
-//     crypto.RegisterHash(crypto.SHA3_384, New384)
-//     crypto.RegisterHash(crypto.SHA3_512, New512)
-
 const (
 	dsbyteSHA3   = 0b00000110
 	dsbyteKeccak = 0b00000001