dt-bindings: arm: ti: Add bindings for AM642 SK

AM642 StarterKit (SK) board is a low cost, small form factor board
designed for TI’s AM642 SoC.
Add DT binding documentation for AM642 SK.
Signed-off-by: Lokesh Vutla <lokeshvutla@ti.com>
Signed-off-by: Nishanth Menon <nm@ti.com>
Tested-by: Kishon Vijay Abraham I <kishon@ti.com>
Acked-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20210226184251.26451-2-lokeshvutla@ti.com

Documentation/devicetree/bindings/arm/ti/k3.yaml

@@ -37,6 +37,7 @@ properties:
         items:
           - enum:
               - ti,am642-evm
+              - ti,am642-sk
           - const: ti,am642
 
 additionalProperties: true