ethdev: attach or detach port

ethdev: attach or detach port

These functions are used for attaching or detaching a port.
When rte_eth_dev_attach() is called, the function tries to realize the
device name as pci address. If this is done successfully,
rte_eth_dev_attach() will attach physical device port. If not, attaches
virtual devive port.
When rte_eth_dev_detach() is called, the function gets the device type
of this port to know whether the port is come from physical or virtual.
And then specific detaching function will be called.

Signed-off-by: Tetsuya Mukawa <mukawa@igel.co.jp>