dt-bindings: bus: add stm32mp21 RIFSC compatible

The STM32MP21x platforms have a slightly different RIFSC. While its
core functionalities are similar, the wiring is not the same. Hence,
declare a new compatible.

Signed-off-by: Gatien Chevallier <gatien.chevallier@foss.st.com>
Acked-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20251106-rifsc_debugfs-v2-1-f90e94ae756d@foss.st.com
Signed-off-by: Alexandre Torgue <alexandre.torgue@foss.st.com>

Author: GseoC

Documentation/devicetree/bindings/bus/st,stm32mp25-rifsc.yaml

@@ -33,14 +33,18 @@ select:
   properties:
     compatible:
       contains:
-        const: st,stm32mp25-rifsc
+        enum:
+          - st,stm32mp21-rifsc
+          - st,stm32mp25-rifsc
   required:
     - compatible
 
 properties:
   compatible:
     items:
-      - const: st,stm32mp25-rifsc
+      - enum:
+          - st,stm32mp21-rifsc
+          - st,stm32mp25-rifsc
       - const: simple-bus
 
   reg: