Preliminary support for the zed/zynq platform, for control-plane-only
hdl/assemblies/testbias/Makefile: add zed exclusion since it doesn't have a data plane
hdl/assemblies/testbias2/Makefile: ditto
hdl/assemblies/testbias5/Makefile: ditto
hdl/assemblies/testbias_ver/Makefile: ditto
hdl/platforms/zed/* add the initial control-plane-only zed platform