ASoC: rt1015: add delay to fix pop noise from speaker

Add delay to fix pop noise from speaker.

Signed-off-by: Jack Yu <jack.yu@realtek.com>
Reviewed-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Link: https://lore.kernel.org/r/20201105030804.31115-1-jack.yu@realtek.com
Signed-off-by: Mark Brown <broonie@kernel.org>

Documentation/devicetree/bindings/sound/rt1015.txt

@@ -8,10 +8,16 @@ Required properties:
 
 - reg : The I2C address of the device.
 
+Optional properties:
+
+- realtek,power-up-delay-ms
+  Set a delay time for flush work to be completed,
+  this value is adjustable depending on platform.
 
 Example:
 
 rt1015: codec@28 {
 	compatible = "realtek,rt1015";
 	reg = <0x28>;
+	realtek,power-up-delay-ms = <50>;
 };