ASoC: rt1015: Fix the failure to flush DAC data before playback

Fix the failure to flush DAC data before playback.

Signed-off-by: derek.fang <derek.fang@realtek.com>
Link: https://lore.kernel.org/r/1600073839-6762-2-git-send-email-derek.fang@realtek.com


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