pcie: Don't return error if no PCIe present

Resolves openbmc/bmcweb#98

Tested:

Before the fix:
curl -k -H "X-Auth-Token: $TOKEN" -X GET https://${BMC_IP}/redfish/v1/Systems/system
{
  "@odata.context": "/redfish/v1/$metadata#ComputerSystem.ComputerSystem",
  "@odata.id": "/redfish/v1/Systems/system",
  "@odata.type": "#ComputerSystem.v1_6_0.ComputerSystem",
...
  "SystemType": "Physical",
  "error": {
    "@Message.ExtendedInfo": [
      {
        "@odata.type": "/redfish/v1/$metadata#Message.v1_0_0.Message",
        "Message": "The request failed due to an internal service error.  The service is still operational.",
        "MessageArgs": [],
        "MessageId": "Base.1.4.0.InternalError",
        "Resolution": "Resubmit the request.  If the problem persists, consider resetting the service.",
        "Severity": "Critical"
      }
    ],
    "code": "Base.1.4.0.InternalError",
    "message": "The request failed due to an internal service error.  The service is still operational."
  }

After the fix:
curl -k -H "X-Auth-Token: $TOKEN" -X GET https://${BMC_IP}/redfish/v1/Systems/system
{
  "@odata.context": "/redfish/v1/$metadata#ComputerSystem.ComputerSystem",
  "@odata.id": "/redfish/v1/Systems/system",
  "@odata.type": "#ComputerSystem.v1_6_0.ComputerSystem",
...
  "SerialNumber": "1318ECA",
  "Status": {
    "Health": "OK",
    "HealthRollup": "OK",
    "State": "Disabled"
  },
  "SystemType": "Physical"
}

Change-Id: I0cc2a86decdea47164103c901ce7bd631f8adaf2
Signed-off-by: Andrew Geissler <geissonator@yahoo.com>
diff --git a/redfish-core/lib/pcie.hpp b/redfish-core/lib/pcie.hpp
index 6b8600f..ad61ff4 100644
--- a/redfish-core/lib/pcie.hpp
+++ b/redfish-core/lib/pcie.hpp
@@ -35,9 +35,9 @@
                     std::vector<std::string> &pcieDevicePaths) {
             if (ec)
             {
-                BMCWEB_LOG_DEBUG << "failed to get PCIe device paths ec: "
+                BMCWEB_LOG_DEBUG << "no PCIe device paths found ec: "
                                  << ec.message();
-                messages::internalError(asyncResp->res);
+                // Not an error, system just doesn't have PCIe info
                 return;
             }
             nlohmann::json &pcieDeviceList =