dt-bindings: power: bcm-pmb: add BCM63138 binding

PMB can be also found on bcm63xx chipsets. It uses difference device
addresses so a new binding is required.
Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>

Documentation/devicetree/bindings/power/brcm,bcm-pmb.yaml

@@ -16,6 +16,7 @@ properties:
   compatible:
     enum:
       - brcm,bcm4908-pmb
+      - brcm,bcm63138-pmb
 
   reg:
     description: register space of one or more buses