ASoC: rt700: wait for the delayed work to finish when the system suspends

To avoid the IO error, we need to cancel the delayed work and wait for it to finish.

Signed-off-by: Shuming Fan <shumingf@realtek.com>
Reviewed-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Link: https://lore.kernel.org/r/20200921094244.31869-1-shumingf@realtek.com
Signed-off-by: Mark Brown <broonie@kernel.org>