dt-bindings: arm: stm32: Add compatibles for syscon nodes

Since commit ad440432d1f9 ("dt-bindings: mfd: Ensure 'syscon' has a more specific compatible")
it is required to provide at least 2 compatibles string for syscon node.
This patch document the missing compatibles for stm32 SoCs.

Signed-off-by: Benjamin Gaignard <[e-mail]>
Reviewed-by: Rob Herring <[e-mail]>
Signed-off-by: Alexandre Torgue <[e-mail]>

Documentation/devicetree/bindings/arm/stm32/st,stm32-syscon.yaml

···
       - items:
           - enum:
               - st,stm32mp157-syscfg
+              - st,stm32mp151-pwr-mcu
+              - st,stm32-syscfg
+              - st,stm32-power-config
           - const: syscon
 
   reg:
···
 required:
   - compatible
   - reg
-  - clocks
+
+if:
+  properties:
+    compatible:
+      contains:
+        enum:
+          - st,stm32mp157-syscfg
+then:
+  required:
+    - clocks
 
 additionalProperties: false