checkpatch: avoid some commit message long line warnings

checkpatch: avoid some commit message long line warnings

Fixes: and Link: lines may exceed 75 chars in the commit log.
So too can stack dump and dmesg lines and lines that seem
like filenames.

And Fixes: lines don't need to have a "commit" prefix before the
commit id.

Add exceptions for these types of lines.

Signed-off-by: Joe Perches <[email protected]>
Reported-by: Paul Bolle <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>