Fix PowerSupply GET error

The commit 3e42a3290ae35f05b30fa1863f44e95845577420[1] mistakenly
handled a check of then given powersupply id, and caused Redfish Service
Validator error.

Tested:
- Verify GET
```
curl -k https://${bmc}/redfish/v1/Chassis/chassis/PowerSubsystem/PowerSupplies/powersupply0
```

- Redfish Service Validator on PowerSupplies passes
```
python3 RedfishServiceValidator.py --auth Session -i https://${bmc} -u ${user} -p ${password} \
        --payload Tree /redfish/v1/Chassis/chassis/PowerSubsystem/PowerSupplies
```

[1] https://github.com/openbmc/bmcweb/commit/3e42a3290ae35f05b30fa1863f44e95845577420

Change-Id: I9abfadc5f1ad5a0fd05e596190678aa804259045
Signed-off-by: Myung Bae <myungbae@us.ibm.com>
diff --git a/redfish-core/lib/power_supply.hpp b/redfish-core/lib/power_supply.hpp
index f934a3b..f085272 100644
--- a/redfish-core/lib/power_supply.hpp
+++ b/redfish-core/lib/power_supply.hpp
@@ -161,7 +161,7 @@
     for (const auto& [objectPath, service] : subtree)
     {
         sdbusplus::message::object_path path(objectPath);
-        if (path == powerSupplyId)
+        if (path.filename() == powerSupplyId)
         {
             callback(path, service.begin()->first);
             return;