spi: lpspi: Add power-domains to the DT bindings

i.MX8(X) based SoC use a power domain. Allow supplying this domain in
bindings.
Signed-off-by: Alexander Stein <alexander.stein@ew.tq-group.com>
Acked-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20230721111020.1234278-2-alexander.stein@ew.tq-group.comSigned-off-by: Mark Brown <broonie@kernel.org>

Documentation/devicetree/bindings/spi/spi-fsl-lpspi.yaml

@@ -63,6 +63,9 @@ properties:
     maximum: 2
     default: 1
 
+  power-domains:
+    maxItems: 1
+
 required:
   - compatible
   - reg