bloblist: Relicense to allow BSD-3-Clause

This implementation is intended to be copied to other projects and
modified, to as to foster a standard means of communcating runtime
information between firmware projects.

The GPL-2 license is too restrictive for some projects, e.g. those
intended as reference implementations rather than designed for
collaborative open-source development.

Update the license to make this easier to share.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/include/bloblist.h b/include/bloblist.h
index 798babe..173129b 100644
--- a/include/bloblist.h
+++ b/include/bloblist.h
@@ -1,4 +1,4 @@
-/* SPDX-License-Identifier: GPL-2.0+ */
+/* SPDX-License-Identifier: GPL-2.0+ BSD-3-Clause */
 /*
  * This provides a standard way of passing information between boot phases
  * (TPL -> SPL -> U-Boot proper.)