[PATCH v1 1/2] dts: move *.rst to BSD-3 license to match DPDK

[Honnappa Nagarahalli]

<snip>

> 
> Replace licenses in rst files with the same license that's used in
> DPDK. The format is:
> .. SPDX-License-Identifier: BSD-3-Clause
>    Copyright(c) <year>[-<end-year>] <contributor>
> 
> Signed-off-by: Juraj Linkeš <juraj.linkes at pantheon.tech>
Reviewed-by: Honnappa Nagarahalli <honnappa.nagarahalli at arm.com>

> ---

<snip>