linux-imx

MLK-15960-2: ASoC: fsl_sai: refine the pm runtime function

In imx8qm/imx8qxp, the power domain of IP is enabled when
pm_runtime_get_sync() is called, and disabled when pm_runtime
_put_sync() is called. when power domain is disabled, the value
of registers will lost, so we need to use the regcache_sync()
to restore the registers in fsl_sai_runtime_resume.

Signed-off-by: Shengjiu Wang <shengjiu.wang@freescale.com>