ASoC: es8316: add DT-bindings

This patch adds missing DT-bindings document for Everest ES8316.
Signed-off-by: Katsuhiro Suzuki <katsuhiro@katsuster.net>
Link: https://lore.kernel.org/r/20190903165322.20791-4-katsuhiro@katsuster.netSigned-off-by: Mark Brown <broonie@kernel.org>

Documentation/devicetree/bindings/sound/everest,es8316.txt

+Everest ES8316 audio CODEC
+
+This device supports both I2C and SPI.
+
+Required properties:
+
+  - compatible  : should be "everest,es8316"
+  - reg : the I2C address of the device for I2C
+  - clocks : a list of phandle, should contain entries for clock-names
+  - clock-names : should include as follows:
+         "mclk" : master clock (MCLK) of the device
+
+Example:
+
+es8316: codec@11 {
+	compatible = "everest,es8316";
+	reg = <0x11>;
+	clocks = <&clks 10>;
+	clock-names = "mclk";
+};