dt-bindings: rng: introduce new compatible for STM32MP13x

Introduce st,stm32mp13-rng compatible and add st,rng-lock-conf.

If st,rng-lock-conf is set, the RNG configuration in RNG_CR, RNG_HTCR
and RNG_NSCR will be locked. It is supported starting from the RNG
version present in the STM32MP13

Signed-off-by: Gatien Chevallier <gatien.chevallier@foss.st.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

Documentation/devicetree/bindings/rng/st,stm32-rng.yaml

@@ -15,7 +15,9 @@ maintainers:
 
 properties:
   compatible:
-    const: st,stm32-rng
+    enum:
+      - st,stm32-rng
+      - st,stm32mp13-rng
 
   reg:
     maxItems: 1
@@ -30,11 +32,27 @@ properties:
     type: boolean
     description: If set enable the clock detection management
 
+  st,rng-lock-conf:
+    type: boolean
+    description: If set, the RNG configuration in RNG_CR, RNG_HTCR and
+                  RNG_NSCR will be locked.
+
 required:
   - compatible
   - reg
   - clocks
 
+allOf:
+  - if:
+      properties:
+        compatible:
+          contains:
+            enum:
+              - st,stm32-rng
+    then:
+      properties:
+        st,rng-lock-conf: false
+
 additionalProperties: false
 
 examples: