Add description for 'struct regmap *cci' member of struct imx335.

This will fix the following compile-time warning:
warning: Function parameter or struct member 'cci' not described in 'imx335'
Signed-off-by: Umang Jain <umang.jain@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>