ASoC: SOF: debug: Add support for IPC message injection

In order to stress test the firmware's ability to handle (mis)crafted
IPC messages this patch adds a debugfs interface where a binary file
(message) can be written and the message is sent to the firmware as it is.

Read on the same file will return the reply from the firmware if it is
available as a binary.

Signed-off-by: Peter Ujfalusi <peter.ujfalusi@linux.intel.com>
Reviewed-by: Rander Wang <rander.wang@intel.com>
Reviewed-by: Ranjani Sridharan <ranjani.sridharan@linux.intel.com>
Reviewed-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Reviewed-by: Guennadi Liakhovetski <guennadi.liakhovetski@linux.intel.com>
Signed-off-by: Daniel Baluta <daniel.baluta@nxp.com>
Link: https://lore.kernel.org/r/20211116152137.52129-5-daniel.baluta@oss.nxp.com
Signed-off-by: Mark Brown <broonie@kernel.org>