ASoC: fsl_esai doc: Add "fsl,vf610-esai" as compatible string

Since commit b21cc2f5 ("ASoC: esai: Add VF610+ compatibles support.")
the fsl_esai driver also accepts  the "fsl,vf610-esai" compatible string.

Update the documentation accordingly.
Signed-off-by: NFabio Estevam <fabio.estevam@freescale.com>
Acked-by: NNicolin Chen <nicoleotsuka@gmail.com>
Signed-off-by: NMark Brown <broonie@kernel.org>

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

@@ -7,7 +7,8 @@ other DSPs. It has up to six transmitters and four receivers.
 
 Required properties:
 
-  - compatible : Compatible list, must contain "fsl,imx35-esai".
+  - compatible : Compatible list, must contain "fsl,imx35-esai" or
+		 "fsl,vf610-esai"
 
   - reg : Offset and length of the register set for the device.