eth/filters: remove unused struct fields (#24782)

Author: hero5512

eth/filters/api.go

@@ -29,7 +29,6 @@ import (
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/common/hexutil"
 	"github.com/ethereum/go-ethereum/core/types"
-	"github.com/ethereum/go-ethereum/event"
 	"github.com/ethereum/go-ethereum/rpc"
 )
 
@@ -48,8 +47,6 @@ type filter struct {
 // information related to the Ethereum protocol such als blocks, transactions and logs.
 type PublicFilterAPI struct {
 	backend   Backend
-	mux       *event.TypeMux
-	quit      chan struct{}
 	events    *EventSystem
 	filtersMu sync.Mutex
 	filters   map[rpc.ID]*filter