To make software license auditing simpler, use SPDX[0] license
identifiers instead of duplicating the license text in every file.

NOTE: Files that have been imported by FreeBSD have not been modified.

[0]: https://spdx.org/

Change-Id: I80a00e1f641b8cc075ca5a95b10607ed9ed8761a
Signed-off-by: dp-arm <dimitris.papastamos@arm.com>

So far, there are more and more features are supported on the RK3399,
meanwhile, these features are increasingly being defined and intertwined.
It's time to clean up and make them clearer.

Signed-off-by: Xing Zheng <zhengxing@rock-chips.com>