Revert "Implement Redfish PCIeSlots schema"

This reverts commit 7691cc2f7ef1f0ceedf3de0554045a614f25776d.

This causes validator failures
ERROR - JsonSchemas: GET of resource at URI /redfish/v1/JsonSchemas returned HTTP 404. Check URI.
ERROR - PCIeSlots: GET of resource at URI /redfish/v1/Chassis/motherboard/PCIeSlots returned HTTP 404. Check URI.
ERROR - PCIeSlots: GET of resource at URI /redfish/v1/Chassis/chassis/PCIeSlots returned HTTP 404. Check URI.

Change-Id: Ibcdf238a222da83127a89d8f38c8180501ffe882
Signed-off-by: Ed Tanous <edtanous@google.com>
diff --git a/redfish-core/lib/pcie.hpp b/redfish-core/lib/pcie.hpp
index 8437f50..b4d6433 100644
--- a/redfish-core/lib/pcie.hpp
+++ b/redfish-core/lib/pcie.hpp
@@ -129,8 +129,9 @@
     {
         return "Gen5";
     }
-    if (generationInUse ==
-        "xyz.openbmc_project.Inventory.Item.PCIeSlot.Generations.Unknown")
+    if (generationInUse.empty() ||
+        generationInUse ==
+            "xyz.openbmc_project.Inventory.Item.PCIeSlot.Generations.Unknown")
     {
         return "";
     }