ASoC: Intel: sof_cs42l42: always set dpcm_capture for amplifiers

The amplifier may provide hardware support for I/V feedback, or
alternatively the firmware may generate an echo reference attached to
the SSP and dailink used for the amplifier.

To avoid any issues with invalid/NULL substreams in the latter case,
always unconditionally set dpcm_capture.

Link: thesofproject#4083
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Reviewed-by: Ranjani Sridharan <ranjani.sridharan@linux.intel.com>
Reviewed-by: Péter Ujfalusi <peter.ujfalusi@linux.intel.com>
Reviewed-by: Bard Liao <yung-chuan.liao@linux.intel.com>
Signed-off-by: Kai Vehmanen <kai.vehmanen@linux.intel.com>
Link: https://lore.kernel.org/r/20230119163459.2235843-3-kai.vehmanen@linux.intel.com
Signed-off-by: Mark Brown <broonie@kernel.org>

Author: plbossart

sound/soc/intel/boards/sof_cs42l42.c

@@ -336,6 +336,9 @@ static int create_spk_amp_dai_links(struct device *dev,
 	links[*id].platforms = platform_component;
 	links[*id].num_platforms = ARRAY_SIZE(platform_component);
 	links[*id].dpcm_playback = 1;
+	/* firmware-generated echo reference */
+	links[*id].dpcm_capture = 1;
+
 	links[*id].no_pcm = 1;
 	links[*id].cpus = &cpus[*id];
 	links[*id].num_cpus = 1;