ASoC: fsl_audmix: rework runtime PM handling in probe

In the Linux kernel, the following vulnerability has been resolved: ASoC: fsl_audmix: rework runtime PM handling in probe After pm_runtime_enable() the AUDMIX block is powered off and stays suspended until the first runtime resume. Register writes issued between probe() and the first resume (e.g. from DAPM or ALSA control paths) target unpowered hardware and cause a system hang. Fix this by calling pm_runtime_resume_and_get() immediately after pm_runtime_enable() to power the hardware up and enable its clocks. Release the reference afterwards with pm_runtime_put() to allow the runtime PM framework to suspend the device and switch the regmap to cache-only mode when idle. When CONFIG_PM is disabled or runtime PM is not enabled, pm_runtime_* calls are stubs that do not power up the hardware. Handle this case explicitly by calling fsl_audmix_runtime_resume() directly so the hardware is always initialised and its clocks are enabled, ensuring register accesses succeed regardless of PM configuration.