wallet: refactor: inline function WriteOrderPos()

Since accounts were removed in commit c9c32e6b84,
this function is only called at one place and thus can be as well inlined.

src/wallet/transaction.h

@@ -19,14 +19,6 @@
 
 typedef std::map<std::string, std::string> mapValue_t;
 
-
-static inline void WriteOrderPos(const int64_t& nOrderPos, mapValue_t& mapValue)
-{
-    if (nOrderPos == -1)
-        return;
-    mapValue["n"] = ToString(nOrderPos);
-}
-
 /** Legacy class used for deserializing vtxPrev for backwards compatibility.
  * vtxPrev was removed in commit 93a18a3650292afbb441a47d1fa1b94aeb0164e3,
  * but old wallet.dat files may still contain vtxPrev vectors of CMerkleTxs.
@@ -181,7 +173,9 @@ public:
         mapValue_t mapValueCopy = mapValue;
 
         mapValueCopy["fromaccount"] = "";
-        WriteOrderPos(nOrderPos, mapValueCopy);
+        if (nOrderPos != -1) {
+            mapValueCopy["n"] = ToString(nOrderPos);
+        }
         if (nTimeSmart) {
             mapValueCopy["timesmart"] = strprintf("%u", nTimeSmart);
         }