Made a testbench for ddrctrl (transient buffer function).

...ns/lofar2_unb2c_ddrctrl/src/vhdl/lofar2_unb2c_ddrctrl.vhd

.../lofar2_unb2c_ddrctrl/tb/vhdl/tb_lofar2_unb2c_ddrctrl.vhd

applications/lofar2/libraries/ddrctrl/src/vhdl/ddrctrl.vhd

.../lofar2/libraries/ddrctrl/src/vhdl/ddrctrl_controller.vhd

...ions/lofar2/libraries/ddrctrl/src/vhdl/ddrctrl_output.vhd

...far2/libraries/ddrctrl/src/vhdl/ddrctrl_output_unpack.vhd

applications/lofar2/libraries/ddrctrl/tb/vhdl/tb_ddrctrl.vhd

libraries/base/diag/src/vhdl/diag_data_buffer_dev.vhd