MAINTAINERS: update imi,rdacm2x-gmsl.yaml reference

The file name: Documentation/devicetree/bindings/media/i2c/rdacm2x-gmsl.yaml
should be, instead: Documentation/devicetree/bindings/media/i2c/imi,rdacm2x-gmsl.yaml.

Update its cross-reference accordingly.

Fixes: 34009bff ("media: i2c: Add RDACM20 driver")
Fixes: e9f81768 ("media: dt-bindings: media: i2c: Add bindings for IMI RDACM2x")
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>