Fix using wrong flag for railtype restricted signal custom sprite enabled

src/newgrf_railtype.cpp

@@ -153,7 +153,7 @@ static PalSpriteID GetRailTypeCustomSignalSprite(const RailtypeInfo *rti, TileIn
 CustomSignalSpriteResult GetCustomSignalSprite(const RailtypeInfo *rti, TileIndex tile, SignalType type, SignalVariant var, uint8 aspect, bool gui, bool restricted)
 {
 	PalSpriteID spr = GetRailTypeCustomSignalSprite(rti, tile, type, var, aspect, gui, restricted);
-	if (spr.sprite != 0) return { spr, HasBit(rti->ctrl_flags, RTCF_PROGSIG) };
+	if (spr.sprite != 0) return { spr, HasBit(rti->ctrl_flags, RTCF_RESTRICTEDSIG) };
 
 	for (const GRFFile *grf : _new_signals_grfs) {
 		if (type == SIGTYPE_PROG && !HasBit(grf->new_signal_ctrl_flags, NSCF_PROGSIG)) continue;