ASoC: nau8825: add pm function

This patch adds pm function and fixes following issues
1.i2c timeout after resume, after resume we saw interrupt handler
is called prior to i2c controller is resumed.This causes i2c timeout
2.no audio after resume

Signed-off-by: Fang, Yang A <yang.a.fang@intel.com>
Signed-off-by: Yong Zhi <yong.zhi@intel.com>
Signed-off-by: Mark Brown <broonie@kernel.org>