ASoC: rt5682: Enable PLL2 function

Enable RT5682 PLL2 function to implement the more complex
frequency conversion.

Signed-off-by: derek.fang <derek.fang@realtek.com>
Link: https://lore.kernel.org/r/1581577510-1807-1-git-send-email-derek.fang@realtek.com


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