sysdb: be_refresh_get_values_ex() remove unused option
The objectclass argument is not used in be_refresh_get_values_ex()
anymore.
Related to https://pagure.io/SSSD/sssd/issue/3503
Reviewed-by: Fabiano FidĂȘncio <fidencio@redhat.com>
Reviewed-by: Jakub Hrozek <jhrozek@redhat.com>