ALSA: hda: Skip codec shutdown in case the codec is not registered

If the codec->registered is not set then it means that pm_runtime is
not yet enabled and the codec->pcm_list_head has not been initialized.

The access to the not initialized pcm_list_head will lead a kernel crash
during shutdown.

Reported-by: Guennadi Liakhovetski <guennadi.liakhovetski@linux.intel.com>
Signed-off-by: Peter Ujfalusi <peter.ujfalusi@linux.intel.com>
Tested-by: Guennadi Liakhovetski <guennadi.liakhovetski@linux.intel.com>
Fixes: b98444ed

 ("ALSA: hda: Suspend codec at shutdown")
Link: https://lore.kernel.org/r/20220201112144.29411-1-peter.ujfalusi@linux.intel.com
Signed-off-by: Takashi Iwai <tiwai@suse.de>