dsp_driver=4 will force the AVS driver stack to be used, it is better to
docuement this.

Fixes: 1affc44e ("ASoC: Intel: avs: PCI driver implementation")
Signed-off-by: Peter Ujfalusi <peter.ujfalusi@linux.intel.com>
Reviewed-by: Cezary Rojewski <cezary.rojewski@intel.com>
Link: https://lore.kernel.org/r/20240607060021.11503-1-peter.ujfalusi@linux.intel.comSigned-off-by: Takashi Iwai <tiwai@suse.de>