dt-bindings: arm: fsl: Fix Toradex Colibri i.MX 8 binding

The Toradex Colibri i.MX 8 Evaluation board has two Toradex compatibles
so it needs separate entry.  This fixes dtbs_check warning:

  arch/arm64/boot/dts/freescale/imx8qxp-colibri-eval-v3.dt.yaml: /:
    compatible: ['toradex,colibri-imx8x-eval-v3', 'toradex,colibri-imx8x', 'fsl,imx8qxp'] is not valid under any of the given schemas (Possible causes of the failure):
    arch/arm64/boot/dts/freescale/imx8qxp-colibri-eval-v3.dt.yaml: /: compatible: ['toradex,colibri-imx8x-eval-v3', 'toradex,colibri-imx8x', 'fsl,imx8qxp'] is too long

Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>