spi: dt-bindings: snps,dw-apb-ssi: add 'power-domains' property

This SPI controller likely belongs to a power domain for all the SoCs
listed. For sure, it belongs to one on the Renesas RZ/N1 SoC, so
enable the property to be able to describe its power domain in DTs.

Suggested-by: Herve Codina <herve.codina@bootlin.com>
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Reviewed-by: Herve Codina <herve.codina@bootlin.com>
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@oss.qualcomm.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://patch.msgid.link/20260626180326.9593-3-wsa+renesas@sang-engineering.com
Signed-off-by: Mark Brown <broonie@kernel.org>

Author: Wolfram Sang

Documentation/devicetree/bindings/spi/snps,dw-apb-ssi.yaml

@@ -93,6 +93,9 @@ properties:
       - const: ssi_clk
       - const: pclk
 
+  power-domains:
+    maxItems: 1
+
   resets:
     maxItems: 1