dt-bindings: net: ipq4019-mdio: require and validate clocks

Now that we can match the platforms requiring clocks by compatible start
using those to allow clocks per compatible and make them required.

Signed-off-by: Robert Marko <robimarko@gmail.com>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20221114194734.3287854-3-robimarko@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>