host-bmc: host_pdr_handler: Drop unused fruJson

```
../host-bmc/host_pdr_handler.cpp:33:16: error: unused variable 'fruJson' [-Werror,-Wunused-const-variable]
   33 | constexpr auto fruJson = "host_frus.json";
      |                ^~~~~~~
```

Change-Id: Ia04cb6beba4465fa0fa872b84c5b58f05c90ca36
Signed-off-by: Andrew Jeffery <andrew@codeconstruct.com.au>
diff --git a/host-bmc/host_pdr_handler.cpp b/host-bmc/host_pdr_handler.cpp
index 38d3be9..61167ab 100644
--- a/host-bmc/host_pdr_handler.cpp
+++ b/host-bmc/host_pdr_handler.cpp
@@ -30,7 +30,6 @@
 using Json = nlohmann::json;
 namespace fs = std::filesystem;
 using namespace pldm::dbus;
-constexpr auto fruJson = "host_frus.json";
 const Json emptyJson{};
 
 template <typename T>