[PATCH v2 4/5] dts: add ability to start/stop testpmd ports

[Juraj Linkeš]

As Jeremy mentioned, adding the verify argument may be worthwhile, but 
maybe only if we actually identify a usecase where we wouldn't want to 
do the verification.

I also have two other points:
1. Do we want a decorator that does both - starting and stopping? Is the 
idea to have all methods that require a certain state to be decorated 
and in that case we don't need this? E.g. if there are multiple 
configuration steps, only the first one stops the ports (if started) and 
we start the ports only when a method needs that (such as starting pkt 
fwd)? I think this workflow should be documented in the class docstring 
(the important part being that starting and stopping of ports is done 
automatically).
2. Do we want decorators that start/stop just one port? I guess this is 
basically useless with the above workflow.