MAINTAINERS: add ASoC maintainers for sound dt-bindings

Sound dt-bindings are applied by ASoC maintainers and should be
submit to ASoC list in addition to the devicetree list.

Hence, add this information into the MAINTAINERS file.
Signed-off-by: NClément Péron <peron.clem@gmail.com>
Signed-off-by: NMark Brown <broonie@kernel.org>

MAINTAINERS

@@ -13592,6 +13592,7 @@ S:	Supported
 F:	Documentation/devicetree/bindings/sound/
 F:	Documentation/sound/soc/
 F:	sound/soc/
+F:	include/dt-bindings/sound/
 F:	include/sound/soc*
 
 SOUNDWIRE SUBSYSTEM