mfd: google,cros-ec: Fix property name for MediaTek rpmsg

The MediaTek rpmsg-name is defined as mediatek,rpmsg-name in
mtk,scp.yaml. Fix the binding documentation to match the new property
Signed-off-by: Matthias Brugger <matthias.bgg@gmail.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Link: https://lore.kernel.org/r/20211218081543.3851-1-matthias.bgg@kernel.org

Documentation/devicetree/bindings/mfd/google,cros-ec.yaml

@@ -59,7 +59,7 @@ properties:
       whether this nvram is present or not.
     type: boolean
 
-  mtk,rpmsg-name:
+  mediatek,rpmsg-name:
     description:
       Must be defined if the cros-ec is a rpmsg device for a Mediatek
       ARM Cortex M4 Co-processor. Contains the name pf the rpmsg