[media] atmel-isi: setup YCC_SWAP correctly when using preview path

The preview path only can convert UYVY format to RGB data.

To make preview path work correctly, we need to set up YCC_SWAP
according to sensor output and convert them to UYVY.

Signed-off-by: Josh Wu <josh.wu@atmel.com>
Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>