ASoC: dt-bindings: fsl_rpmsg: Add compatible string for i.MX93

Add compatible string for i.MX93 platform which supports audio
function through rpmsg channel between Cortex-A and Cortex-M core.
Signed-off-by: Chancel Liu <chancel.liu@nxp.com>
Acked-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20230714092913.1591195-2-chancel.liu@nxp.comSigned-off-by: Mark Brown <broonie@kernel.org>

Documentation/devicetree/bindings/sound/fsl,rpmsg.yaml

@@ -25,6 +25,7 @@ properties:
       - fsl,imx8mm-rpmsg-audio
       - fsl,imx8mp-rpmsg-audio
       - fsl,imx8ulp-rpmsg-audio
+      - fsl,imx93-rpmsg-audio
 
   model:
     $ref: /schemas/types.yaml#/definitions/string