io-mapping: Indicate mapping failure

[Andy Shevchenko]

On Tue, Jul 21, 2020 at 11:34:25AM -0400, Michael J. Ruhl wrote:
> I found this when my system crashed long after the mapping failure.
> The expected behavior should have been driver exit.
> 
> Since this is almost exclusively used for drm, I am posting to
> the dri mailing list.  Should this go to another list as well?

Just drop this cover letter. For single patch is not needed. Use place
immediately after cutter '---' line for comments like above.

-- 
With Best Regards,
Andy Shevchenko