Scripts are adapted for SW HW decouple

To avoid openwifi-hw github submodule in openwifi. More flexible now.

minor update on xilinx dma driver related stuffs

remove our customized xilinx_dma.c. the original xilinx_dma.c in kernel can be used now

Fix various typos

Found via codespell v2.1.dev0
`codespell -q 3 -L ans,filp,fils,hsi`

Update xilinx_dma.c

Update make_xilinx_dma.sh

Update README.md

adding license and copyright headers

Update README.md

prepare upgrade

initial commit