ASoC: SOF: topology: Use struct_size() helper

Make use of the struct_size() helper instead of an open-coded version
in order to avoid any potential type mistakes, in particular in the
context in which this code is being used.

So, replace the following form:

sizeof(struct sof_ipc_ctrl_data) + sizeof(struct sof_ipc_ctrl_value_chan) *
	le32_to_cpu(mc->num_channels)

with:

struct_size(scontrol->control_data, chanv, le32_to_cpu(mc->num_channels))

and so on...

This code was detected with the help of Coccinelle.
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

sound/soc/sof/topology.c

@@ -442,9 +442,8 @@ static int sof_control_load_volume(struct snd_soc_component *scomp,
 		return -EINVAL;
 
 	/* init the volume get/put data */
-	scontrol->size = sizeof(struct sof_ipc_ctrl_data) +
-			 sizeof(struct sof_ipc_ctrl_value_chan) *
-			 le32_to_cpu(mc->num_channels);
+	scontrol->size = struct_size(scontrol->control_data, chanv,
+				     le32_to_cpu(mc->num_channels));
 	scontrol->control_data = kzalloc(scontrol->size, GFP_KERNEL);
 	if (!scontrol->control_data)
 		return -ENOMEM;
@@ -501,9 +500,8 @@ static int sof_control_load_enum(struct snd_soc_component *scomp,
 		return -EINVAL;
 
 	/* init the enum get/put data */
-	scontrol->size = sizeof(struct sof_ipc_ctrl_data) +
-			 sizeof(struct sof_ipc_ctrl_value_chan) *
-			 le32_to_cpu(ec->num_channels);
+	scontrol->size = struct_size(scontrol->control_data, chanv,
+				     le32_to_cpu(ec->num_channels));
 	scontrol->control_data = kzalloc(scontrol->size, GFP_KERNEL);
 	if (!scontrol->control_data)
 		return -ENOMEM;