media: imx.rst: Fix the MIPI CSI-2 virtual channel

The current instructions for imx6q-sabresd do not lead to functional
capture on OV5640 MIPI CSI-2.

The reason for this, as explained by Steve Longerbeam, is that OV5640 by
default transmits on virtual channel 0, not channel 1 as is given in the
instructions.

Adapt the instructions to use virtual channel 0 so that a working
camera setup can be achieved on imx6q-sabresd.

Also, since we are using an IC direct conversion pipeline, improve
the example by demonstrating colorspace and scaling.

Signed-off-by: Fabio Estevam <festevam@gmail.com>
Reviewed-by: Steve <Longerbeam&lt;slongerbeam@gmail.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>