dt-bindings: spi: add reference file to YAML

In JH7110 SoC, the spi module needs to use "arm,primecell-periphid" to
override the h/w ID value to  correctly init "spi_dev", so add
"primecell.yaml" as the reference file for YAML.
Signed-off-by: William Qiu <william.qiu@starfivetech.com>
Link: https://lore.kernel.org/r/20230724101054.25268-2-william.qiu@starfivetech.comSigned-off-by: Mark Brown <broonie@kernel.org>

Documentation/devicetree/bindings/spi/spi-pl022.yaml

@@ -11,6 +11,7 @@ maintainers:
 
 allOf:
   - $ref: spi-controller.yaml#
+  - $ref: /schemas/arm/primecell.yaml#
 
 # We need a select here so we don't match all nodes with 'arm,primecell'
 select: