media: i2c: Fix pixel array positions in ov8865

The ov8865's datasheet gives the pixel array as 3296x2528, and the
active portion as the centre 3264x2448. This makes for a top offset
of 40 and a left offset of 16, not 32 and 80.

Fixes: acd25e22 ("media: i2c: Add .get_selection() support to ov8865")

Reported-by: Jean-Michel Hautbois <jeanmichel.hautbois@ideasonboard.com>
Signed-off-by: Daniel Scally <djrscally@gmail.com>
Reviewed-by: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>
Reviewed-by: Paul Kocialkowski <paul.kocialkowski@bootlin.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>