ASoC: SOF: imx8: add core shutdown operation for imx8/imx8x

ASoC: SOF: imx8: add core shutdown operation for imx8/imx8x

Currently, the DSP core from i.MX8QM/i.MX8QXP is able to operate while the
firmware image is being loaded. Because of this, the DSP may change the
content of the firmware data just after it was loaded, thus leading to the
data having unexpected values when the DSP is reset (via run()).

Fix this by implementing the core_shutdown() operation that will put the
DSP in stall during suspend(). The stall will be removed during the run()
opertion, thus guaranteeing that the DSP core will not be able to run
while the firmware image is being loaded.

Signed-off-by: Laurentiu Mihalcea <laurentiu.mihalcea@nxp.com>
Reviewed-by: Daniel Baluta <daniel.baluta@nxp.com>
Link: https://patch.msgid.link/20250613194310.1128733-1-laurentiumihalcea111@gmail.com
Signed-off-by: Mark Brown <broonie@kernel.org>