Add cable test support

Add support for starting a cable test, and report the results.

This code does not follow the usual patterns because of the way the
kernel reports the results of the cable test. It can take a number of
seconds for cable testing to occur. So the action request messages is
immediately acknowledges, and the test is then performed asynchronous.
Once the test has completed, the results are returned as a
notification.

This means the command starts as usual. It then monitors multicast
messages until it receives the results.

Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Michal Kubecek <mkubecek@suse.cz>
6 files changed