dt-bindings: net: convert qca,qca7000.txt yaml format

dt-bindings: net: convert qca,qca7000.txt yaml format

Convert qca,qca7000.txt yaml format.

Additional changes:
- add refs: spi-peripheral-props.yaml, serial-peripheral-props.yaml and
  ethernet-controller.yaml.
- simple spi and uart node name.
- use low case for mac address in examples.
- add check reg choose spi-peripheral-props.yaml or
  spi-peripheral-props.yaml.

Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Frank Li <Frank.Li@nxp.com>
Link: https://patch.msgid.link/20250618184417.2169745-1-Frank.Li@nxp.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>