Don't build examples from source code checked into meta data

[wmamills]

Currently the source code rpsmg openamp library samples are checked into the meta data and built from there.
The openamp library repo also has much the same sample code and this layer should build the samples from there and delete the local source code.

If the samples at open-amp repo need to be enhanced, they should be enhanced/fixed in that repo.

[edmooring]

Agreed. This is unexpected and confusing behavior.