Let's try to run checkpatch in an open-source and fast way while
leveraging Github's very good user interface.
Run checkpatch both with and without --strict; this has been a source of
confusion in the past, see
https://github.com/thesofproject/linux/pull/1988
Note this attempt does not rely on git merge-bases which has been found
to be not compatible with shallow cloning:
https://github.com/thesofproject/linux/issues/2556
Signed-off-by: Marc Herbert <marc.herbert@intel.com>