media: i2c: imx290: Replace V4L2_CID_GAIN with V4L2_CID_ANALOGUE_GAIN

Most software (including libcamera) requires V4L2_CID_ANALOGUE_GAIN,
not V4L2_CID_GAIN.

The range for the control is 0 to 100 for which the sensor uses only
analogue gain; higher values would involve digital gain which this
control should not apply.

Signed-off-by: David Plowman <david.plowman@raspberrypi.com>