ASoC: SOF: Convert the generic IPC flood test into SOF client

Move the IPC flood test code out from the debug file as separate SOF client
driver.

Based on the kernel configuration, the device registration for the new IPC
flood test is going to happen in the core.
With the separate client driver it is going to be possible to run multiple
flood tests in parallel to increase the stress, the new Kconfig option can
be used to select this (defaults to 1).
In order to preserve backward compatibility with existing SW/scripts, the
first IPC flood test's debugfs files have been linked to the old files.

Signed-off-by: Ranjani Sridharan <ranjani.sridharan@linux.intel.com>
Co-developed-by: Fred Oh <fred.oh@linux.intel.com>
Signed-off-by: Fred Oh <fred.oh@linux.intel.com>
Signed-off-by: Peter Ujfalusi <peter.ujfalusi@linux.intel.com>
Reviewed-by: Kai Vehmanen <kai.vehmanen@linux.intel.com>
Reviewed-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Reviewed-by: Ranjani Sridharan <ranjani.sridharan@linux.intel.com>
Link: https://lore.kernel.org/r/20220210150525.30756-8-peter.ujfalusi@linux.intel.com
Signed-off-by: Mark Brown <broonie@kernel.org>