dt-bindings: clock: samsung: convert Exynos542x to dtschema

Merge Exynos542x clock controller bindings to existing DT schema.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Reviewed-by: Sam Protsenko <semen.protsenko@linaro.org>
Link: https://lore.kernel.org/r/20210825134056.219884-4-krzysztof.kozlowski@canonical.com
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>

Author: krzk

Documentation/devicetree/bindings/clock/exynos5420-clock.txt

@@ -18,7 +18,14 @@ description: |
 
 properties:
   compatible:
-    const: samsung,exynos5250-clock
+    oneOf:
+      - enum:
+          - samsung,exynos5250-clock
+      - items:
+          - enum:
+              - samsung,exynos5420-clock
+              - samsung,exynos5800-clock
+          - const: syscon
 
   clocks:
     maxItems: 4