dt-bindings: arm: rockchip: add PX30-PP1516 boards from Theobroma Systems

PP1516 are Touchscreen devices built around the PX30 SoC and companion
devices to PX30-Cobra, again with multiple display options.

The devices feature an EMMC, OTG port and a 720x1280 display with a
touchscreen and camera

Signed-off-by: Heiko Stuebner <heiko.stuebner@cherry.de>
Acked-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: Quentin Schulz <quentin.schulz@cherry.de>
Link: https://lore.kernel.org/r/20250514150745.2437804-6-heiko@sntech.de
Signed-off-by: Heiko Stuebner <heiko@sntech.de>

Author: Heiko Stuebner

Documentation/devicetree/bindings/arm/rockchip.yaml

@@ -1136,6 +1136,14 @@ properties:
           - const: tsd,px30-cobra
           - const: rockchip,px30
 
+      - description: Theobroma Systems PX30-PP1516
+        items:
+          - enum:
+              - tsd,px30-pp1516-ltk050h3146w-a2
+              - tsd,px30-pp1516-ltk050h3148w
+          - const: tsd,px30-pp1516
+          - const: rockchip,px30
+
       - description: Theobroma Systems PX30-uQ7 with Haikou baseboard
         items:
           - const: tsd,px30-ringneck-haikou