Just pass a hash to AddInventoryKnown

Since it's only used for transactions, there's no need to pass in an inv type.

src/net.h

@@ -965,11 +965,11 @@ public:
     }
 
 
-    void AddInventoryKnown(const CInv& inv)
+    void AddInventoryKnown(const uint256& hash)
     {
         if (m_tx_relay != nullptr) {
             LOCK(m_tx_relay->cs_tx_inventory);
-            m_tx_relay->filterInventoryKnown.insert(inv.hash);
+            m_tx_relay->filterInventoryKnown.insert(hash);
         }
     }