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>