Remove unused fields from sealing

extern/storage-sealing/sealing.go

@@ -106,9 +106,6 @@ type Sealing struct {
 	assignedPieces map[abi.SectorID][]cid.Cid
 	creating       *abi.SectorNumber // used to prevent a race where we could create a new sector more than once
 
-	upgradeLk sync.Mutex
-	toUpgrade map[abi.SectorNumber]struct{}
-
 	notifee SectorStateNotifee
 	addrSel AddrSel
 
@@ -168,7 +165,6 @@ func New(mctx context.Context, api SealingAPI, fc config.MinerFeeConfig, events
 		sectorTimers:   map[abi.SectorID]*time.Timer{},
 		pendingPieces:  map[cid.Cid]*pendingPiece{},
 		assignedPieces: map[abi.SectorID][]cid.Cid{},
-		toUpgrade:      map[abi.SectorNumber]struct{}{},
 
 		notifee: notifee,
 		addrSel: as,