ASoC: SOF: Revert: "core: unregister clients and machine drivers in .shutdown"

The unregister machine drivers call is not safe to do when
kexec is used. Kexec-lite gets blocked with following backtrace:

[   84.943749] Freezing user space processes ... (elapsed 0.111 seconds) done.
[  246.784446] INFO: task kexec-lite:5123 blocked for more than 122 seconds.
[  246.819035] Call Trace:
[  246.821782]  <TASK>
[  246.824186]  __schedule+0x5f9/0x1263
[  246.828231]  schedule+0x87/0xc5
[  246.831779]  snd_card_disconnect_sync+0xb5/0x127
...
[  246.889249]  snd_sof_device_shutdown+0xb4/0x150
[  246.899317]  pci_device_shutdown+0x37/0x61
[  246.903990]  device_shutdown+0x14c/0x1d6
[  246.908391]  kernel_kexec+0x45/0xb9

This reverts commit 83bfc7e.

Reported-by: Ricardo Ribalda <[email protected]>
Cc: Ricardo Ribalda <[email protected]>
Signed-off-by: Kai Vehmanen <[email protected]>
Reviewed-by: Pierre-Louis Bossart <[email protected]>
Reviewed-by: Péter Ujfalusi <[email protected]>
Reviewed-by: Ranjani Sridharan <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Mark Brown <[email protected]>

Author: kv2019i

sound/soc/sof/core.c

@@ -475,19 +475,10 @@ EXPORT_SYMBOL(snd_sof_device_remove);
 int snd_sof_device_shutdown(struct device *dev)
 {
 	struct snd_sof_dev *sdev = dev_get_drvdata(dev);
-	struct snd_sof_pdata *pdata = sdev->pdata;
 
 	if (IS_ENABLED(CONFIG_SND_SOC_SOF_PROBE_WORK_QUEUE))
 		cancel_work_sync(&sdev->probe_work);
 
-	/*
-	 * make sure clients and machine driver(s) are unregistered to force
-	 * all userspace devices to be closed prior to the DSP shutdown sequence
-	 */
-	sof_unregister_clients(sdev);
-
-	snd_sof_machine_unregister(sdev, pdata);
-
 	if (sdev->fw_state == SOF_FW_BOOT_COMPLETE)
 		return snd_sof_shutdown(sdev);