Documentation: arm64: Add Hisilicon Hip07 D05 dts binding

This patch adds documentation for the devicetree bindings used by
the DT files of Hisilicon Hip07 D05 board.

Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: Wei Xu <xuwei5@hisilicon.com>