ASoC: meson: axg-tdm-formatter: add reset to the bindings documentation

Add an optional reset property to the tdm formatter bindings. The
dedicated reset line is present on some SoC families, such as the g12a.
Signed-off-by: Jerome Brunet <jbrunet@baylibre.com>
Link: https://lore.kernel.org/r/20190703120749.32341-2-jbrunet@baylibre.comSigned-off-by: Mark Brown <broonie@kernel.org>

Documentation/devicetree/bindings/sound/amlogic,axg-tdm-formatters.txt

@@ -15,11 +15,15 @@ Required properties:
   * "lrclk"    : sample clock
   * "lrclk_sel": sample clock input multiplexer
 
-Example of TDMOUT_A on the A113 SoC:
+Optional property:
+- resets: phandle to the dedicated reset line of the tdm formatter.
+
+Example of TDMOUT_A on the S905X2 SoC:
 
 tdmout_a: audio-controller@500 {
 	compatible = "amlogic,axg-tdmout";
 	reg = <0x0 0x500 0x0 0x40>;
+	resets = <&clkc_audio AUD_RESET_TDMOUT_A>;
 	clocks = <&clkc_audio AUD_CLKID_TDMOUT_A>,
 		 <&clkc_audio AUD_CLKID_TDMOUT_A_SCLK>,
 		 <&clkc_audio AUD_CLKID_TDMOUT_A_SCLK_SEL>,