arm64: dts: imx8mm-beacon-kit: add DVDD-supply and DOVDD-supply

According to binding doc, DVDD-supply and DOVDD-supply is required
properties. Add these to fix below warning:
arch/arm64/boot/dts/freescale/imx8mm-beacon-kit.dtb: camera@10: 'DVDD-supply' is a required proper

Signed-off-by: Frank Li <Frank.Li@nxp.com>
Reviewed-by: Adam Ford <aford173@gmail.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>