[openssl/openssl] 0a12ab: Update Docs for EVP_MAC

[Neil Horman]

  Branch: refs/heads/openssl-3.1
  Home:   https://github.com/openssl/openssl
  Commit: 0a12aba18f705c888d661d2e2da3848a392f70a5
      https://github.com/openssl/openssl/commit/0a12aba18f705c888d661d2e2da3848a392f70a5
  Author: Neil Horman <nhorman at openssl.org>
  Date:   2024-01-11 (Thu, 11 Jan 2024)

  Changed paths:
    M doc/man3/EVP_MAC.pod

  Log Message:
  -----------
  Update Docs for EVP_MAC

For GMAC/CMAC, its not possible to re-init the algorithm without
explicitly passing an OSSL_MAC_PARAM_IV to each init call, as it is
not possible to extract the IV value from the prior init call (be it
explicitly passed or auto generated).  As such, document the fact that
re-initalization requires passing an IV parameter

Reviewed-by: Matt Caswell <matt at openssl.org>
Reviewed-by: Tomas Mraz <tomas at openssl.org>
(Merged from https://github.com/openssl/openssl/pull/23235)

(cherry picked from commit 7c1d533a512181b13de3bc0b7fa2fd8c481032d3)