ASoC: dt-bindings: fsl-sai: Add compatible string for imx8mm/8mn/8mp/8ulp

Add compatible string for imx8mm/8mn/8mp/8ulp, these platforms all
support SAI IP.
Signed-off-by: Shengjiu Wang <shengjiu.wang@nxp.com>
Acked-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/1622613770-10220-1-git-send-email-shengjiu.wang@nxp.comSigned-off-by: Mark Brown <broonie@kernel.org>

Documentation/devicetree/bindings/sound/fsl-sai.txt

@@ -9,8 +9,10 @@ Required properties:
 
   - compatible		: Compatible list, contains "fsl,vf610-sai",
 			  "fsl,imx6sx-sai", "fsl,imx6ul-sai",
-			  "fsl,imx7ulp-sai", "fsl,imx8mq-sai" or
-			  "fsl,imx8qm-sai".
+			  "fsl,imx7ulp-sai", "fsl,imx8mq-sai",
+			  "fsl,imx8qm-sai", "fsl,imx8mm-sai",
+			  "fsl,imx8mn-sai", "fsl,imx8mp-sai", or
+			  "fsl,imx8ulp-sai".
 
   - reg			: Offset and length of the register set for the device.