[SSSD] [sssd PR#612][comment] crypto: Silence a Coverity warning in sss_hmac_sha1()

[sumit-bose]

  URL: https://github.com/SSSD/sssd/pull/612
Title: #612: crypto: Silence a Coverity warning in sss_hmac_sha1()

sumit-bose commented:
"""
Ok, Coverity didn't complain about new errors and CI passed as well. ACK
"""

See the full comment at https://github.com/SSSD/sssd/pull/612#issuecomment-404155244