ASoC: wm_adsp: mark more data structures with the const qualifier

ASoC: wm_adsp: mark more data structures with the const qualifier

The callback structures and memory region type table can be marked as
const as they will not change during use.

Fix checkpatch warning against wm_adsp_find_region function by moving
const keyword to form the 'static const struct' pattern.

Signed-off-by: Simon Trimmer <simont@opensource.cirrus.com>
Acked-by: Charles Keepax <ckeepax@opensource.cirrus.com>
Link: https://lore.kernel.org/r/20210511171459.270169-1-simont@opensource.cirrus.com
Signed-off-by: Mark Brown <broonie@kernel.org>