multi: add reset closure to kvdb.Update

Similarly as with kvdb.View this commits adds a reset closure to the
kvdb.Update call in order to be able to reset external state if the
underlying db backend needs to retry the transaction.

htlcswitch/decayedlog.go

@@ -131,7 +131,7 @@ func (d *DecayedLog) initBuckets() error {
 		}
 
 		return nil
-	})
+	}, func() {})
 }
 
 // Stop halts the garbage collector and closes boltdb.