media: MAINTAINERS: Fix sort order for RDACM20

The files maintained as part of the RDACM20 were incorrectly sorted
while they were added.

Correct the sort-order.

Fixes: 34009bff

 ("media: i2c: Add RDACM20 driver")
Signed-off-by: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>
Acked-by: Jacopo Mondi <jacopo@jmondi.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>