[openssl/openssl] 31fc8a: Fix coverity alert on use of uninitialised data

[Matt Caswell]

  Branch: refs/heads/master
  Home:   https://github.com/openssl/openssl
  Commit: 31fc8a83bc9aa435ae40c3eff713ced441eaa011
      https://github.com/openssl/openssl/commit/31fc8a83bc9aa435ae40c3eff713ced441eaa011
  Author: Matt Caswell <matt at openssl.org>
  Date:   2023-10-05 (Thu, 05 Oct 2023)

  Changed paths:
    M providers/implementations/digests/blake2_prov.c
    M providers/implementations/digests/blake2b_prov.c

  Log Message:
  -----------
  Fix coverity alert on use of uninitialised data

The function `ossl_blake2b_param_init` should initialise only, and not
read the data it is initialising

Reviewed-by: Richard Levitte <levitte at openssl.org>
Reviewed-by: Paul Dale <pauli at openssl.org>
Reviewed-by: Tomas Mraz <tomas at openssl.org>
(Merged from https://github.com/openssl/openssl/pull/22282)