ASoC: dt-bindings: rt5682: add button delay device property

The btndet-delay device property could control the HW debounce time.
It is easy to adjust the sensitivity of push button.

Signed-off-by: Shuming Fan <shumingf@realtek.com>
Link: https://lore.kernel.org/r/20191030085556.14351-1-shumingf@realtek.com


Signed-off-by: Mark Brown <broonie@kernel.org>