ASoC: wm_adsp: Switch to using wm_coeff_read_ctrl for compressed buffers

ASoC: wm_adsp: Switch to using wm_coeff_read_ctrl for compressed buffers

When parsing a compressed buffer from the firmware the driver currently
open codes reading the firmware coefficient containing the buffer
description. Improve this slightly by using the coefficient read
functions already provided by the wm_adsp driver. It is worth noting
this change requires the running variable to be set before
wm_adsp_buffer_init is called, however this is safe, since its all still
under the power lock and nothing in the compressed code gates itself on
running.

Signed-off-by: Charles Keepax <ckeepax@opensource.cirrus.com>
Signed-off-by: Simon Trimmer <simont@opensource.cirrus.com>
Link: https://lore.kernel.org/r/20210913160057.103842-4-simont@opensource.cirrus.com
Signed-off-by: Mark Brown <broonie@kernel.org>