Fix double deletion in `passes/hierarchy/hierarchy.cc`.
Fix double deletion in `passes/hierarchy/hierarchy.cc`.

Co-Authored-By: Eddie Hung <bacc1c505cb1756c59242c0a8ee25cd990a210e9@fpgeh.com>

cliffordwolf/yosys,antmicro/yosys,YosysHQ/yosys,cliffordwolf/yosys,YosysHQ/yosys,cliffordwolf/yosys,SymbiFlow/yosys,YosysHQ/yosys,SymbiFlow/yosys,antmicro/yosys,YosysHQ/yosys,YosysHQ/yosys,YosysHQ/yosys,antmicro/yosys,SymbiFlow/yosys,cliffordwolf/yosys,antmicro/yosys,cliffordwolf/yosys,YosysHQ/yosys,cliffordwolf/yosys,SymbiFlow/yosys,SymbiFlow/yosys,SymbiFlow/yosys,cliffordwolf/yosys,antmicro/yosys,antmicro/yosys,SymbiFlow/yosys,antmicro/yosys,YosysHQ/yosys,SymbiFlow/yosys,antmicro/yosys,cliffordwolf/yosys,cliffordwolf/yosys