Hisilicon Network Subsystem NIC controller

Required properties:
- compatible: "hisilicon,hns-nic-v1" or "hisilicon,hns-nic-v2".
  "hisilicon,hns-nic-v1" is for hip05.
  "hisilicon,hns-nic-v2" is for Hi1610 and Hi1612.
- ae-name: accelerator name who provides this interface,
  is simply a name referring to the name of name in the accelerator node.
- port-id: is the index of port provided by DSAF (the accelerator). DSAF can
  connect to 8 PHYs. Port 0 to 1 are both used for adminstration purpose. They
  are called debug ports.

  The remaining 6 PHYs are taken according to the mode of DSAF.

  In NIC mode of DSAF, all 6 PHYs are taken as ethernet ports to the CPU. The
  port-id can be 2 to 7. Here is the diagram:
            +-----+---------------+
            |            CPU      |
            +-+-+-+---+-+-+-+-+-+-+
              | |     | | | | | |
             debug       service
             port         port
             (0,1)       (2-7)

  In Switch mode of DSAF, all 6 PHYs are taken as physical ports connect to a
  LAN Switch while the CPU side assume itself have one single NIC connect to
  this switch. In this case, the port-id will be 2 only.
            +-----+---------------+
            |            CPU      |
            +-+-+-+---+-+-+-+-+-+-+
              | |   service| port(2)
             debug   +------------+
             port    |   switch   |
             (0,1)   +-+-+-+-+-+-++
                       | | | | | |
                      external port

- local-mac-address: mac addr of the ethernet interface

Example:

	ethernet@0{
		compatible = "hisilicon,hns-nic-v1";
		ae-name = "dsaf0";
		port-id = <0>;
		local-mac-address = [a2 14 e4 4b 56 76];
	};