Convert the wkup_m3_ipc bindings documentation to json-schema.

Link: https://lore.kernel.org/linux-arm-kernel/20220221125522.l3tntb6i7yjxp6vb@flattered/Suggested-by: NNishanth Menon <nm@ti.com>
Reviewed-by: NKrzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: NDrew Fustini <dfustini@baylibre.com>
Signed-off-by: NRob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20220407154618.2297171-1-dfustini@baylibre.com