ASoC: dt-bindings: fsl_asrc: add compatible string for imx8qm & imx8qxp

Add compatible string "fsl,imx8qm-asrc" for imx8qm platform,
"fsl,imx8qxp-asrc" for imx8qxp platform.

There are two asrc modules in imx8qm & imx8qxp, the clock mapping is
different for each other, so add new property "fsl,asrc-clk-map"
to distinguish them.
Signed-off-by: Shengjiu Wang <shengjiu.wang@nxp.com>
Acked-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/b9352edb014c1ee8530c0fd8829c2b044b3da649.1575452454.git.shengjiu.wang@nxp.comSigned-off-by: Mark Brown <broonie@kernel.org>

Documentation/devicetree/bindings/sound/fsl,asrc.txt

@@ -8,7 +8,12 @@ three substreams within totally 10 channels.
 
 Required properties:
 
-  - compatible		: Contains "fsl,imx35-asrc" or "fsl,imx53-asrc".
+  - compatible		: Compatible list, should contain one of the following
+			  compatibles:
+			  "fsl,imx35-asrc",
+			  "fsl,imx53-asrc",
+			  "fsl,imx8qm-asrc",
+			  "fsl,imx8qxp-asrc",
 
   - reg			: Offset and length of the register set for the device.
 
@@ -35,6 +40,11 @@ Required properties:
 
    - fsl,asrc-width	: Defines a mutual sample width used by DPCM Back Ends.
 
+   - fsl,asrc-clk-map   : Defines clock map used in driver. which is required
+			  by imx8qm/imx8qxp platform
+			  <0> - select the map for asrc0 in imx8qm/imx8qxp
+			  <1> - select the map for asrc1 in imx8qm/imx8qxp
+
 Optional properties:
 
    - big-endian		: If this property is absent, the little endian mode