ASoC: dt-bindings: Introduce compatible strings for 7ULP and 8MQ

For i.MX7ULP and i.MX8MQ register map is changed. Add two new compatbile
strings to differentiate this.
Signed-off-by: Daniel Baluta <daniel.baluta@nxp.com>
Acked-by: Nicolin Chen <nicoleotsuka@gmail.com>
Link: https://lore.kernel.org/r/20190806151214.6783-6-daniel.baluta@nxp.comSigned-off-by: Mark Brown <broonie@kernel.org>

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

@@ -8,7 +8,8 @@ codec/DSP interfaces.
 Required properties:
 
   - compatible		: Compatible list, contains "fsl,vf610-sai",
-			  "fsl,imx6sx-sai" or "fsl,imx6ul-sai"
+			  "fsl,imx6sx-sai", "fsl,imx6ul-sai",
+			  "fsl,imx7ulp-sai" or "fsl,imx8mq-sai".
 
   - reg			: Offset and length of the register set for the device.