media: dt-bindings: sh-mobile-ceu: Remove now unimplemented bindings documentation

Remove the SH Mobile CEU bindings documentation as the corresponding driver
was removed v5.1 by the following commit:

43a445f1 ("media: sh_mobile_ceu_camera: remove obsolete soc_camera driver")
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
Acked-by: Rob Herring <robh@kernel.org>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>

Documentation/devicetree/bindings/media/sh_mobile_ceu.txt

-Bindings, specific for the sh_mobile_ceu_camera.c driver:
- - compatible: Should be "renesas,sh-mobile-ceu"
- - reg: register base and size
- - interrupts: the interrupt number
- - renesas,max-width: maximum image width, supported on this SoC
- - renesas,max-height: maximum image height, supported on this SoC
-
-Example:
-
-ceu0: ceu@fe910000 {
-	compatible = "renesas,sh-mobile-ceu";
-	reg = <0xfe910000 0xa0>;
-	interrupt-parent = <&intcs>;
-	interrupts = <0x880>;
-	renesas,max-width = <8188>;
-	renesas,max-height = <8188>;
-};