ASoC: SOF: topology: add min/max step for volume_table

add two units min_volume_step and max_volume_step to the snd_sof_control
struct, for the min and max step of the volume_table.
Signed-off-by: Zhu Yingjiang <yingjiang.zhu@linux.intel.com>
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

sound/soc/sof/sof-priv.h

@@ -297,6 +297,8 @@ struct snd_sof_pcm {
 struct snd_sof_control {
 	struct snd_sof_dev *sdev;
 	int comp_id;
+	int min_volume_step; /* min volume step for volume_table */
+	int max_volume_step; /* max volume step for volume_table */
 	int num_channels;
 	u32 readback_offset; /* offset to mmaped data if used */
 	struct sof_ipc_ctrl_data *control_data;

sound/soc/sof/topology.c

@@ -451,6 +451,8 @@ static int sof_control_load_volume(struct snd_soc_component *scomp,
 		return -ENOMEM;
 
 	scontrol->comp_id = sdev->next_comp_id;
+	scontrol->min_volume_step = le32_to_cpu(mc->min);
+	scontrol->max_volume_step = le32_to_cpu(mc->max);
 	scontrol->num_channels = le32_to_cpu(mc->num_channels);
 
 	/* set cmd for mixer control */