Currently, there are several ADV7535 dt-schema warnings.

Fx them the same way as in commit efa97aed ("arm64: dts:
imx8mm-evk: Fix hdmi@3d node").

As there are two different PMICs used on the imx8mn-evk variants,
describe the ADV7535 power supplies in each board devicetree.

Fixes: 5aafda60 ("arm64: dts: imx8mn-evk: Add camera support")
Signed-off-by: Fabio Estevam <festevam@denx.de>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>