passes/hierarchy: delete some dead code
passes/hierarchy: delete some dead code

Signed-off-by: Austin Seipp <48c905ac3851f382b914247d97dd93273d5ff555@pobox.com>

antmicro/yosys,antmicro/yosys,SymbiFlow/yosys,YosysHQ/yosys,cliffordwolf/yosys,SymbiFlow/yosys,YosysHQ/yosys,cliffordwolf/yosys,SymbiFlow/yosys,swallat/yosys,swallat/yosys,azonenberg/yosys,cliffordwolf/yosys,swallat/yosys,swallat/yosys,SymbiFlow/yosys,antmicro/yosys,SymbiFlow/yosys,antmicro/yosys,swallat/yosys,cliffordwolf/yosys,SymbiFlow/yosys,antmicro/yosys,azonenberg/yosys,swallat/yosys,swallat/yosys,cliffordwolf/yosys,YosysHQ/yosys,antmicro/yosys,antmicro/yosys,cliffordwolf/yosys,YosysHQ/yosys,swallat/yosys,swallat/yosys,SymbiFlow/yosys,cliffordwolf/yosys,azonenberg/yosys,YosysHQ/yosys,SymbiFlow/yosys,azonenberg/yosys,YosysHQ/yosys,YosysHQ/yosys,cliffordwolf/yosys,cliffordwolf/yosys,azonenberg/yosys,azonenberg/yosys,azonenberg/yosys,antmicro/yosys,azonenberg/yosys,YosysHQ/yosys,azonenberg/yosys