This renames the dcdofs config option in the imx-image tool to ivtofs.  dcdofs
is a misnomer. The DCD (Device Configuration Data) is only one part of the data
linked into the IVT (Image Vector Table), but the meaning of the option is
really the latter, not the former.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

This creates an image that can be booted via USB.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>