ASoC: SOF: Intel: Rename deprecated DMIC IPC struct field

This patch restores the field name to fifo_bits_b since the
legacy firmware compatibility code (for firmware ABI 3.0.0 or earlier)
sets it in sof_link_dmic_load() function in topology.c. Setting of
reserved_2 didn't look appropriate.

Signed-off-by: Seppo Ingalsuo <seppo.ingalsuo@linux.intel.com>
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Reviewed-by: Kai Vehmanen <kai.vehmanen@linux.intel.com>
Reviewed-by: Guennadi Liakhovetski <guennadi.liakhovetski@linux.intel.com>
Link: https://lore.kernel.org/r/20200415202816.934-19-pierre-louis.bossart@linux.intel.com
Signed-off-by: Mark Brown <broonie@kernel.org>

include/sound/sof/dai-intel.h

@@ -173,7 +173,7 @@ struct sof_ipc_dai_dmic_params {
 	uint32_t fifo_fs;	/**< FIFO sample rate in Hz (8000..96000) */
 	uint32_t reserved_1;	/**< Reserved */
 	uint16_t fifo_bits;	/**< FIFO word length (16 or 32) */
-	uint16_t reserved_2;	/**< Reserved */
+	uint16_t fifo_bits_b;	/**< Deprecated since firmware ABI 3.0.1 */
 
 	uint16_t duty_min;	/**< Min. mic clock duty cycle in % (20..80) */
 	uint16_t duty_max;	/**< Max. mic clock duty cycle in % (min..80) */

sound/soc/sof/topology.c

@@ -2957,10 +2957,12 @@ static int sof_link_dmic_load(struct snd_soc_component *scomp, int index,
 			config->dmic.pdm[j].skew);
 	}
 
-	if (SOF_ABI_VER(v->major, v->minor, v->micro) < SOF_ABI_VER(3, 0, 1)) {
-		/* this takes care of backwards compatible handling of fifo_bits_b */
-		config->dmic.reserved_2 = config->dmic.fifo_bits;
-	}
+	/*
+	 * this takes care of backwards compatible handling of fifo_bits_b.
+	 * It is deprecated since firmware ABI version 3.0.1.
+	 */
+	if (SOF_ABI_VER(v->major, v->minor, v->micro) < SOF_ABI_VER(3, 0, 1))
+		config->dmic.fifo_bits_b = config->dmic.fifo_bits;
 
 	/* send message to DSP */
 	ret = sof_ipc_tx_message(sdev->ipc, config->hdr.cmd, config, size,