I have no evidence for this byte being used this way, and lots of
counterexamples.  Restore the struct to its empirical definition and
patch up gmbus setup to match.
Signed-off-by: NAdam Jackson <ajax@redhat.com>
Acked-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NKeith Packard <keithp@keithp.com>