Fixed a bug in the new feature of $readmem[hb] when an empty string is provided
Fixed a bug in the new feature of $readmem[hb] when an empty string is provided

Signed-off-by: Rodrigo Alejandro Melo <9115257fd96058a415f7c09f9a45c6a6876e4da8@gmail.com>

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