drm/doc: missing SPDX license identifier (Was: Re: [PATCH v5] drm/doc: device hot-unplug for userspace)

[Emil Velikov]

Hi Pekka,

Thanks for the patch - merged to drm-misc-next.
While applying the patch the following warning popped-up.

-:37: WARNING:SPDX_LICENSE_TAG: Missing or malformed
SPDX-License-Identifier tag in line 1
#37: FILE: Documentation/gpu/drm-uapi.rst:1:
+.. Copyright 2020 DisplayLink (UK) Ltd.
                                   │--

Upon closer look, it seems that the DRM documentation lacks a license.
An SPDX one at least - I haven't done extensive reading through each
individual file.
I guess we should add one - be that GPL-2.0, MIT and/or otherwise.
Since I haven't contributed such that much on the documentation side,
I'll defer the suggestion to the maintainers.

Daniel, Dave, care to do the honours?

Tl;DR: the DRM documentation is missing SPDX license identifier.

Thanks
Emil