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.comSigned-off-by: Mark Brown <broonie@kernel.org>