Update README.license since files now have SPDX tags rather than license
text. Adding a copy of BSD-2-Clause license since that no longer exists
within the project.
Signed-off-by: Rob Herring <robh@kernel.org>
Message-Id: <20190620211944.9378-8-robh@kernel.org>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
