Remove dtbo when freeing overlay (#1301)
Remove dtbo when freeing overlay (#1301)


Xilinx/PYNQ,Xilinx/PYNQ,cathalmccabe/PYNQ,Xilinx/PYNQ,Xilinx/PYNQ,Xilinx/PYNQ,cathalmccabe/PYNQ,schelleg/PYNQ,cathalmccabe/PYNQ,cathalmccabe/PYNQ,schelleg/PYNQ,schelleg/PYNQ,cathalmccabe/PYNQ,schelleg/PYNQ,schelleg/PYNQ,cathalmccabe/PYNQ