OTP: failed search for the user of last token emits an error message
    
    This patch fixes the following defect reported by covscan:
    
    """
    Error: CHECKED_RETURN (CWE-252):
    /daemons/ipa-slapi-plugins/ipa-otp-lasttoken/ipa_otp_lasttoken.c:119:
    check_return: Calling "slapi_search_internal_get_entry" without checking
    return value (as is done elsewhere 14 out of 16 times).
    /daemons/ipa-slapi-plugins/ipa-enrollment/ipa_enrollment.c:402:
    example_checked: Example 1: "slapi_search_internal_get_entry(sdn, NULL,
    &config_entry, ipaenrollment_plugin_id)" has its value checked in "(rc =
    slapi_search_internal_get_entry(sdn, NULL, &config_entry,
    ipaenrollment_plugin_id)) != 0".
    /daemons/ipa-slapi-plugins/ipa-lockout/ipa_lockout.c:207:
    example_assign: Example 2: Assigning: "ret" = return value from
    "slapi_search_internal_get_entry(sdn, NULL, &config_entry, getPluginID())".
    /daemons/ipa-slapi-plugins/ipa-lockout/ipa_lockout.c:212:
    example_checked: Example 2 (cont.): "ret" has its value checked in "ret".
    /daemons/ipa-slapi-plugins/ipa-pwd-extop/common.c:651:
    example_assign: Example 3: Assigning: "search_result" = return value from
    "slapi_search_internal_get_entry(sdn, attrlist, e2, ipapwd_plugin_id)".
    /daemons/ipa-slapi-plugins/ipa-pwd-extop/common.c:653:
    example_checked: Example 3 (cont.): "search_result" has its value checked in
    "search_result != 0".
    /daemons/ipa-slapi-plugins/ipa-pwd-extop/prepost.c:1035:
    example_assign: Example 4: Assigning: "ret" = return value from
    "slapi_search_internal_get_entry(tmp_dn, NULL, &pwdop->pwdata.target,
    ipapwd_plugin_id)".
    /daemons/ipa-slapi-plugins/ipa-pwd-extop/prepost.c:1039:
    example_checked: Example 4 (cont.): "ret" has its value checked in "ret != 0".
    /daemons/ipa-slapi-plugins/ipa-uuid/ipa_uuid.c:817:
    example_assign: Example 5: Assigning: "ret" = return value from
    "slapi_search_internal_get_entry(tmp_dn, NULL, &e, getPluginID())".
    /daemons/ipa-slapi-plugins/ipa-uuid/ipa_uuid.c:820:
    example_checked: Example 5 (cont.): "ret" has its value checked in "ret ==
    10".
    """
    
    this patch is a part of a series related to
    https://fedorahosted.org/freeipa/ticket/4795
    
    Reviewed-By: Alexander Bokovoy <abokovoy@redhat.com>