ARM: dts: stm32: add required supplies of ov5640 in stm32mp157c-ev1

Correct the following warnings by adding the required supplies (AVDD, DVDD)
for the ov5640 node.

arch/arm/boot/dts/stm32mp157c-ev1.dtb: camera@3c: 'AVDD-supply' is a required property
From schema: Documentation/devicetree/bindings/media/i2c/ovti,ov5640.yaml
arch/arm/boot/dts/stm32mp157c-ev1.dtb: camera@3c: 'DVDD-supply' is a required property
From schema: Documentation/devicetree/bindings/media/i2c/ovti,ov5640.yaml

Signed-off-by: Alain Volmat <alain.volmat@foss.st.com>
Signed-off-by: Alexandre Torgue <alexandre.torgue@foss.st.com>