We've discussed this a bit internally now and decided that the best way
to version OpenCores cores is to use the SVN commit ID of the rtl/
directory in the project's repository. So, for your tiny-spi project,
the last SVN commit to update the rtl/ directory was commit number 2;
hence, I'd recommend you use the following device tree identifier:
That's: opencores,<project>-rtl<VCS><commit ID>
As projects are currently in SVN, VCS=svn.
Linux drivers for other OpenCores cores will be updated accordingly.