ARM: dts: r8a7742-iwg21d-q7-dbcm-ca: Add missing camera regulators

make dtbs_check:

    arch/arm/boot/dts/r8a7742-iwg21d-q7-dbcm-ca.dt.yaml: ov5640@3c: 'AVDD-supply' is a required property
	    From schema: Documentation/devicetree/bindings/media/i2c/ovti,ov5640.yaml
    arch/arm/boot/dts/r8a7742-iwg21d-q7-dbcm-ca.dt.yaml: ov5640@3c: 'DVDD-supply' is a required property
	    From schema: Documentation/devicetree/bindings/media/i2c/ovti,ov5640.yaml
    arch/arm/boot/dts/r8a7742-iwg21d-q7-dbcm-ca.dt.yaml: ov5640@3c: 'DOVDD-supply' is a required property
	    From schema: Documentation/devicetree/bindings/media/i2c/ovti,ov5640.yaml

Fix this by describing the missing regulators.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>
Link: https://lore.kernel.org/r/300149c730931914b77e17df6bcce89b67c3005f.1634222546.git.geert+renesas@glider.be