Move getPCIeDeviceList to pcie_util

Currently, getPCIeDeviceList is only used by systems.hpp to obtain the
list of PCIe devices. However, there are plans to use this function in
other parts of the PCIe code as well. To better organize our code and
make the function more reusable, this commit moves getPCIeDeviceList to
pcie_util.hpp, a common location for PCIe-related utilities.

Tested:
'''
curl -k https://$bmc/redfish/v1/Systems/system

{
  "@odata.id": "/redfish/v1/Systems/system",
  "@odata.type": "#ComputerSystem.v1_16_0.ComputerSystem",
  "Actions": {
    "#ComputerSystem.Reset": {
      "@Redfish.ActionInfo": "/redfish/v1/Systems/system/ResetActionInfo",
      "target": "/redfish/v1/Systems/system/Actions/ComputerSystem.Reset"
    }
  },
  .....
  .....
  "PCIeDevices": [
    {
      "@odata.id": "/redfish/v1/Systems/system/PCIeDevices/dp0_drive2"
    },
    {
      "@odata.id": "/redfish/v1/Systems/system/PCIeDevices/dp0_drive3"
    },
    .....
    .....
    {
      "@odata.id": "/redfish/v1/Systems/system/PCIeDevices/pcie_card0"
    },
    {
      "@odata.id": "/redfish/v1/Systems/system/PCIeDevices/pcie_card1"
    },
    {
      "@odata.id": "/redfish/v1/Systems/system/PCIeDevices/pcie_card10"
    },
    .....
    {
      "@odata.id": "/redfish/v1/Systems/system/PCIeDevices/pcie_card9"
    }
  ],
  "PCIeDevices@odata.count": 20,
  .....
  .....
'''

Change-Id: I3aaa5b55e8574929154ffd743db53da6fbaeb75d
Signed-off-by: Lakshmi Yadlapati <lakshmiy@us.ibm.com>
diff --git a/redfish-core/lib/systems.hpp b/redfish-core/lib/systems.hpp
index 573bf88..19444b2 100644
--- a/redfish-core/lib/systems.hpp
+++ b/redfish-core/lib/systems.hpp
@@ -23,12 +23,12 @@
 #include "health.hpp"
 #include "hypervisor_system.hpp"
 #include "led.hpp"
-#include "pcie.hpp"
 #include "query.hpp"
 #include "redfish_util.hpp"
 #include "registries/privilege_registry.hpp"
 #include "utils/dbus_utils.hpp"
 #include "utils/json_utils.hpp"
+#include "utils/pcie_util.hpp"
 #include "utils/sw_utils.hpp"
 #include "utils/time_utils.hpp"
 
@@ -3182,7 +3182,7 @@
         getBootProperties(asyncResp);
         getBootProgress(asyncResp);
         getBootProgressLastStateTime(asyncResp);
-        getPCIeDeviceList(asyncResp, "PCIeDevices");
+        pcie_util::getPCIeDeviceList(asyncResp, "PCIeDevices");
         getHostWatchdogTimer(asyncResp);
         getPowerRestorePolicy(asyncResp);
         getAutomaticRetryPolicy(asyncResp);