ASoC: dt-bindings: nxp,tfa989x: Add tfa9897 support

Document TFA9897 bindings.
Signed-off-by: Vincent Knecht <vincent.knecht@mailoo.org>
Reviewed-by: Stephan Gerhold <stephan@gerhold.net>
Link: https://lore.kernel.org/r/20210528105101.508254-1-vincent.knecht@mailoo.orgSigned-off-by: Mark Brown <broonie@kernel.org>

Documentation/devicetree/bindings/sound/nxp,tfa989x.yaml

@@ -13,6 +13,7 @@ properties:
   compatible:
     enum:
       - nxp,tfa9895
+      - nxp,tfa9897
 
   reg:
     maxItems: 1