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

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>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>