[TF-A] v8-R64 Support Added to TF-A

In the last Tech-Forum, Lauren Wehrmeister and I presented our work on adding Arm v8-R64 support to the TF-A codebase. Our presentation will be added to the Tech-Forum page (TF-A open Tech Forum regular call - Trusted Firmwarehttps://www.trustedfirmware.org/meetings/tf-a-technical-forum/) shortly. In the meantime, however, there are more details about the patches here: https://developer.trustedfirmware.org/w/tf_a/rclasssupportdocs/