media: i2c: imx290: Match kernel coding style on whitespace

Backport from https://patchwork.linuxtv.org/project/linux-media/list/?series=9918



Fix up a couple of coding style issues regarding missing blank
lines after declarations, double blank lines, and incorrect
indentation.

Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>