dt-bindings: arm: cpu: Add Marvell MMP3 SMP enable method

Add the enable method for the second PJ4B core of the Marvell MMP3 SoC.
Signed-off-by: Lubomir Rintel <lkundrak@v3.sk>
Reviewed-by: Rob Herring <robh@kernel.org>

Documentation/devicetree/bindings/arm/cpus.yaml

@@ -189,6 +189,7 @@ properties:
               - marvell,armada-390-smp
               - marvell,armada-xp-smp
               - marvell,98dx3236-smp
+              - marvell,mmp3-smp
               - mediatek,mt6589-smp
               - mediatek,mt81xx-tz-smp
               - qcom,gcc-msm8660