ASoC: bindings: fsl-asoc-card: add compatible string for WM8958 codec

The WM8958 codec is used on i.MX7D val board.

Signed-off-by: Shengjiu Wang <shengjiu.wang@nxp.com>
Link: https://lore.kernel.org/r/1615986303-27959-2-git-send-email-shengjiu.wang@nxp.com
Signed-off-by: Mark Brown <broonie@kernel.org>
diff --git a/Documentation/devicetree/bindings/sound/fsl-asoc-card.txt b/Documentation/devicetree/bindings/sound/fsl-asoc-card.txt
index 90d9e9d..23d83fa 100644
--- a/Documentation/devicetree/bindings/sound/fsl-asoc-card.txt
+++ b/Documentation/devicetree/bindings/sound/fsl-asoc-card.txt
@@ -42,6 +42,8 @@
 
  "fsl,imx-audio-si476x"
 
+ "fsl,imx-audio-wm8958"
+
 Required properties:
 
   - compatible		: Contains one of entries in the compatible list.