[openssl/openssl] cb12a6: Coverity 1513478: negative return

[Pauli]

  Branch: refs/heads/openssl-3.0
  Home:   https://github.com/openssl/openssl
  Commit: cb12a691796372f73c13ac8a3ecb17a8d3a059d9
      https://github.com/openssl/openssl/commit/cb12a691796372f73c13ac8a3ecb17a8d3a059d9
  Author: Pauli <pauli at openssl.org>
  Date:   2022-09-06 (Tue, 06 Sep 2022)

  Changed paths:
    M ssl/tls13_enc.c

  Log Message:
  -----------
  Coverity 1513478: negative return

Reviewed-by: Dmitry Belyavskiy <beldmit at gmail.com>
Reviewed-by: Tomas Mraz <tomas at openssl.org>
Reviewed-by: Hugo Landau <hlandau at openssl.org>
(Merged from https://github.com/openssl/openssl/pull/19126)

(cherry picked from commit 1d1537067304b8c8d87b2df393363b40370ad640)