[openssl/openssl] 25c486: Coverity 1508532: out of bounds access

[Pauli]

  Branch: refs/heads/openssl-3.0
  Home:   https://github.com/openssl/openssl
  Commit: 25c486762daf8a279676e3e98136855e2e021100
      https://github.com/openssl/openssl/commit/25c486762daf8a279676e3e98136855e2e021100
  Author: Pauli <pauli at openssl.org>
  Date:   2022-08-23 (Tue, 23 Aug 2022)

  Changed paths:
    M crypto/dh/dh_pmeth.c

  Log Message:
  -----------
  Coverity 1508532: out of bounds access

Reviewed-by: Tomas Mraz <tomas at openssl.org>
Reviewed-by: Hugo Landau <hlandau at openssl.org>
(Merged from https://github.com/openssl/openssl/pull/19033)

(cherry picked from commit eb7a5cc3454174094c0c09f1d00aec464ce0f786)