spi: dt-bindings: st,stm32-spi: add 'power-domains' property

STM32 SPI may be in a power domain which is the case for the STM32MP2x
based boards. Allow a single 'power-domains' entry for STM32 SPI.

Signed-off-by: Alain Volmat <alain.volmat@foss.st.com>
Link: https://patch.msgid.link/20251215-stm32-spi-mp2x-dt-updates-v1-1-464a5fd20f13@foss.st.com
Signed-off-by: Mark Brown <broonie@kernel.org>

Author: Alain Volmat

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

@@ -96,6 +96,9 @@ properties:
       The region should be defined as child node of the AHB SRAM node
       as per the generic bindings in Documentation/devicetree/bindings/sram/sram.yaml
 
+  power-domains:
+    maxItems: 1
+
   access-controllers:
     minItems: 1
     maxItems: 2