[PATCH] drm/panfrost: Give name to anonymous coredump object union

[Alyssa Rosenzweig]

Have we checked that this actually fixes the Mesa build? If so, R-b.

> Commit 730c2bf4ad39 ("drm/panfrost: Add support for devcoredump")
> introduces one such union, breaking the Mesa build.
> 
> Give it a name, and also rename pan_reg_hdr structure because it will
> always be prefixed by the union name.
> 
> Bug: https://gitlab.freedesktop.org/mesa/mesa/-/issues/7195
> 
> Signed-off-by: Adri??n Larumbe <adrian.larumbe at collabora.com>

In Mesa, we would add a trailer "Fixes: 730c2bf4ad39 ("drm/panfrost: Add
support for devcoredump")". If the kernel does the same (I don't
remember), we should do that here, seeing as the panfrost uapi headers
do need to build as C++.