dt-bindings: arm: fsl: add TQ-Systems LS1021A board

TQMLS102xA is a SOM family using NXP LS1021A CPU family.
MBLS102xA is an evaluation mainboard for this SOM.

Signed-off-by: Matthias Schiffer <matthias.schiffer@tq-group.com>
Signed-off-by: Alexander Stein <alexander.stein@ew.tq-group.com>
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

Author: tq-schiffern

Documentation/devicetree/bindings/arm/fsl.yaml

@@ -1312,6 +1312,16 @@ properties:
               - fsl,ls1021a-twr
           - const: fsl,ls1021a
 
+      - description:
+          TQ-Systems TQMLS102xA is a series of socketable SOM featuring
+          LS102x system-on-chip variants. MBLS102xA mainboard can be used as
+          starterkit.
+        items:
+          - enum:
+              - tq,ls1021a-tqmls1021a-mbls102xa
+          - const: tq,ls1021a-tqmls1021a
+          - const: fsl,ls1021a
+
       - description: LS1028A based Boards
         items:
           - enum: