devicetree: bindings: add new SMP enable method Mediatek SoC

This commit add new cpu enable method "mediatek,mt65xx-smp" and
"mediatek,mt81xx-tz-smp".

Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Yingjoe Chen <yingjoe.chen@mediatek.com>
Signed-off-by: Matthias Brugger <matthias.bgg@gmail.com>

Documentation/devicetree/bindings/arm/cpus.txt

@@ -195,6 +195,8 @@ nodes to be present and contain the properties described below.
 			    "marvell,armada-380-smp"
 			    "marvell,armada-390-smp"
 			    "marvell,armada-xp-smp"
+			    "mediatek,mt6589-smp"
+			    "mediatek,mt81xx-tz-smp"
 			    "qcom,gcc-msm8660"
 			    "qcom,kpss-acc-v1"
 			    "qcom,kpss-acc-v2"