dt-bindings: arm: realtek: Document RTD1619 and Realtek Mjolnir EVB

Define compatible strings for Realtek RTD1619 SoC and Realtek Mjolnir EVB.
Signed-off-by: James Tai <james.tai@realtek.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Andreas Färber <afaerber@suse.de>

Documentation/devicetree/bindings/arm/realtek.yaml

@@ -47,4 +47,10 @@ properties:
               - bananapi,bpi-m4 # Banana Pi BPI-M4
               - realtek,lion-skin # Realtek Lion Skin EVB
           - const: realtek,rtd1395
+
+      # RTD1619 SoC based boards
+      - items:
+          - enum:
+              - realtek,mjolnir # Realtek Mjolnir EVB
+          - const: realtek,rtd1619
 ...