dt-bindings: usb: samsung,exynos-usb2: include usb-hcd schema

Remove parts duplicated with usb-hcd.yaml DT schema and include it
directly.

Reviewed-by: Rob Herring <robh@kernel.org>
Reviewed-by: Alim Akhtar <alim.akhtar@samsung.com>
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20220419121013.250023-1-krzysztof.kozlowski@linaro.org


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>