dt-bindings: samsung: exynos-chipid: Document Exynos850 compatible

Add compatible string for Exynos850 chip-id. While at it, use enum
instead of items/const, to reduce further cluttering of "compatible"
list.

Signed-off-by: Sam Protsenko <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Krzysztof Kozlowski <[email protected]>

Author: Sam Protsenko

Documentation/devicetree/bindings/arm/samsung/exynos-chipid.yaml

@@ -11,8 +11,9 @@ maintainers:
 
 properties:
   compatible:
-    items:
-      - const: samsung,exynos4210-chipid
+    enum:
+      - samsung,exynos4210-chipid
+      - samsung,exynos850-chipid
 
   reg:
     maxItems: 1