Document the i.MX DryIce machine states.
Signed-off-by: NJuergen Borleis <jbe@pengutronix.de>
Signed-off-by: NRobert Schwebel <rsc@pengutronix.de>
[rsc: got NDA clearance from Freescale]
Signed-off-by: NAlexandre Belloni <alexandre.belloni@free-electrons.com>