net/mlx5: spawn ethdev ports on Windows

net/mlx5: spawn ethdev ports on Windows

This commit implements mlx5_dev_spawn() API which allocates an eth
device (struct rte_eth_dev) for each PCI device. When working with
representors virtual functions (as in Linux), one PCI device may spawn
several eth devices: the master device for the main physical function
(PF) and several representors for the virtual functions (VFs).  However,
currently Windows does not work in switch dev mode, therefore, no VFs
are created and no representors are spawned. In this case one eth device
is created per one PCI main port.  In addition to device creation - the
device configuration must be correctly set. The device arguments
(devargs - set by the user) are parsed but they may be overridden by
Windows limitations or hardware configurations. Some associated network
parameters are stored in eth device (e.g. ifindex, MAC address, MTU) and
some callback (e.g. burst functions) are set.

Signed-off-by: Ophir Munk <ophirmu@nvidia.com>
Signed-off-by: Tal Shnaiderman <talshn@nvidia.com>
Acked-by: Matan Azrad <matan@nvidia.com>