net: hns: separate debug dsaf device from service dsaf device

There are two kinds of dsaf device in hns, one is for service ports,
contains crossbar in it, can work under different mode. Another is for
debug port, only can work under "single-port" mode. The current code only
declared a dsaf device for both service ports and debug ports. This patch
separate it to three platform devices.

Here is the diagram of all port in one platform device(old):
                                        CPU
                                         |
                                         |        DSAF(one platform device)
    --------------------------------------------------------------      /
    |                           |                  |      |      |     /
    |                          PPE                PPE    PPE     |    /
    |                           |                  |      |      |   /
    |                           |                  |      |      |  /
    |                        crossbar              |      |      | /
    |                           |                  |      |      |/
    |    -----------------------------------       |      |      |
    |    |      |      |      |      |      |      |      |      |
    |    |      |      |      |      |      |      |      |      |
    |   MAC    MAC    MAC    MAC    MAC    MAC    MAC    MAC     |
    |    |      |      |      |      |      |      |      |      |
    --------------------------------------------------------------
         |      |      |      |      |      |      |      |
        PHY    PHY    PHY    PHY    PHY    PHY    PHY    PHY

Here is the diagram of separate all ports to three platform(new):
                                                         CPU
                                                          |
                                    -----------------------------------
                                    |                     |           |
    ----------------------------------------------    ---------   ---------
    |                         |                  |    |       |   |   |   |
    |                        PPE                 |    |  PPE  |   |  PPE  |
    |                         |                  |    |   |   |   |   |   |
    |                         |                  |    |   |   |   |   |   |
    |                      crossbar              |    |   |   |   |   |   |
    |                         |                  |    |   |   |   |   |   |
    |   ----------------------------------       |    |   |   |   |   |   |
    |   |     |     |      |      |      |       |    |   |   |   |   |   |
    |   |     |     |      |      |      |       |    |   |   |   |   |   |
    |  MAC   MAC   MAC    MAC    MAC    MAC      |    |  MAC  |   |  MAC  |
    |   |     |     |      |      |      |       |    |   |   |   |   |   |
    ----------------------------------------------    ---------   ---------
        |     |     |      |      |      |    \        /  |        /  |
       PHY   PHY   PHY    PHY    PHY    PHY    \      /  PHY      /  PHY
                                                \    /           /
                                                 \  /           /
                                             DSAF(three platform device)

Signed-off-by: Daode Huang <huangdaode@hisilicon.com>
Signed-off-by: Yisen Zhuang <yisen.zhuang@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>