app/testpmd: add commands for RSS queue region

app/testpmd: add commands for RSS queue region

This patch add a API configuration of queue region in rss.
It can parse the parameters of region index, queue number,
queue start index, user priority, traffic classes and so on.
According to commands from command line, it will call i40e
private API and start the process of set or flush queue region
configure. As this feature is specific for i40e, so private API
will be used. Aslo add a document for these new commands.
Queue region only support PF by now, so this document is
only for configuration of queue region on PF port.

Signed-off-by: Wei Zhao <wei.zhao1@intel.com>