ASoC: bindings: fsl-asoc-card: Add compatible string for MQS

Add compatible string "fsl,imx-audio-mqs" for MQS, and move
"audio-routing" property to be optional for MQS doesn't need
such property.
Signed-off-by: Shengjiu Wang <shengjiu.wang@nxp.com>
Link: https://lore.kernel.org/r/2185a3ec866bc59f82d93b73d1a732a896fd8f48.1592369271.git.shengjiu.wang@nxp.comSigned-off-by: Mark Brown <broonie@kernel.org>

Documentation/devicetree/bindings/sound/fsl-asoc-card.txt

@@ -34,6 +34,8 @@ The compatible list for this generic sound card currently:
 
  "fsl,imx-audio-wm8960"
 
+ "fsl,imx-audio-mqs"
+
 Required properties:
 
   - compatible		: Contains one of entries in the compatible list.
@@ -44,6 +46,11 @@ Required properties:
 
   - audio-codec		: The phandle of an audio codec
 
+Optional properties:
+
+  - audio-asrc		: The phandle of ASRC. It can be absent if there's no
+			  need to add ASRC support via DPCM.
+
   - audio-routing	: A list of the connections between audio components.
 			  Each entry is a pair of strings, the first being the
 			  connection's sink, the second being the connection's
@@ -60,11 +67,6 @@ Required properties:
 			        coexisting in order to support the old bindings
 				of wm8962 and sgtl5000.
 
-Optional properties:
-
-  - audio-asrc		: The phandle of ASRC. It can be absent if there's no
-			  need to add ASRC support via DPCM.
-
 Optional unless SSI is selected as a CPU DAI:
 
   - mux-int-port	: The internal port of the i.MX audio muxer (AUDMUX)