nvmes.hpp: clean up unused member

clang-tidy issues the following warning:
```
../nvmes.hpp:63:23: warning: private field 'bus' is not used [-Wunused-private-field]
   63 |     sdbusplus::bus_t& bus;
```

Clean up the unused member.

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: Ifba2ac63c2e8f93a89bf7d58024ff544defac3d0
diff --git a/sdbusplus.hpp b/sdbusplus.hpp
index d4f29bc..1cc6de0 100644
--- a/sdbusplus.hpp
+++ b/sdbusplus.hpp
@@ -1,3 +1,5 @@
+#include "config.h"
+
 #include <phosphor-logging/elog-errors.hpp>
 #include <phosphor-logging/elog.hpp>
 #include <phosphor-logging/log.hpp>
@@ -8,8 +10,6 @@
 
 #include <iostream>
 
-#include "config.h"
-
 namespace phosphor
 {
 namespace nvme