crypto/internal/fips140/ecdsa: make TestingOnlyNewDRBG generic

crypto/internal/fips140/ecdsa: make TestingOnlyNewDRBG generic

We are re-sealing the .zip file anyway for another reason, might as well
take the opportunity to remove the fips140.Hash type indirection.

Change-Id: I6a6a6964fdb312cc2c64e327f845c398c0f6279b
Reviewed-on: https://go-review.googlesource.com/c/go/+/701519
Reviewed-by: Michael Pratt <mpratt@google.com>
Reviewed-by: Daniel McCarney <daniel@binaryparadox.net>
Reviewed-by: Mark Freeman <markfreeman@google.com>
TryBot-Bypass: Filippo Valsorda <filippo@golang.org>