ASoC: wm_adsp: Add control_add callback and export wm_adsp_control_add()

The callback allows codec drivers to affect how firmware coefficients
are added as controls.

For example a codec driver may selectively add controls by choosing to
call wm_adsp_control_add() based on some filter logic.

Signed-off-by: Simon Trimmer <simont@opensource.cirrus.com>
Link: https://patch.msgid.link/20240805102721.30102-2-simont@opensource.cirrus.com


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