GPO: Duplicated error message for unreadable GPO
    
    sss_log() had wrong type set as log level.
    The result was error message with very high
    priority displayed on all terminals.
    
    Resolves:
    https://pagure.io/SSSD/sssd/issue/4133
    
    Reviewed-by: Pavel Březina <pbrezina@redhat.com>