format-code: simplify codespell

* Avoid copying codespell config files into the workspace.
* Drop 'ignore-words' support.
* Filter out Signed-off-by lines.

The 'openbmc-spelling-ignore.txt' file contained someone's last
name, which was being triggered by codespell as being similar enough
to a real word that it was identified as a mispelling.  Instead of
keeping their name in an ignore file, filter out the Signed-off-by.

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: Ie2c96a000c352dc02a5dee1db3d2d9ea2b629cef
3 files changed