zxdh: add zxdh poll mode driver

[Stephen Hemminger]

On Mon, 3 Jun 2024 19:28:57 +0800 (CST)
<wang.junlong1 at zte.com.cn> wrote:

> +Prerequisites
> +-------------
> +
> +This PMD driver need NPSDK library for system initialization and allocation of resources.
> +Communication between PMD and kernel modules is mediated by zxdh Kernel modules.
> +The NPSDK library and zxdh Kernel modules are not part of DPDK and must be installed
> +separately:
> +
> +- Getting the latest NPSDK library and software supports using
> +  ``_.

What is the license of the NPSDK ?