dt-bindings: arm: cpus: Allow fsl,soc-operating-points for i.MX6

dt-bindings: arm: cpus: Allow fsl,soc-operating-points for i.MX6

The old i.MX6 (over 10 years) chip use fsl,soc-operating-points to get
SoC's voltage and frequency information when cpu change frequency.

Set fsl,soc-operating-points deprecated.

Allow soc-supply property and set it deprecated.

Fix bunch of CHECK_DTBS warnings:
  arch/arm/boot/dts/nxp/imx/imx6ul-prti6g.dtb: cpu@0 (arm,cortex-a7): Unevaluated properties are not allowed ('fsl,soc-operating-points', 'soc-supply' were unexpected)
	from schema $id: http://devicetree.org/schemas/arm/cpus.yaml#

Signed-off-by: Frank Li <Frank.Li@nxp.com>
Link: https://lore.kernel.org/r/20250827210912.92029-1-Frank.Li@nxp.com
Signed-off-by: Rob Herring (Arm) <robh@kernel.org>