ASoC: wm_adsp: Move check for control existence

Checking earlier in the function if a control already exists avoids
superfluous string construction and also prepares for future
refactoring.

Signed-off-by: Charles Keepax <ckeepax@opensource.cirrus.com>
Signed-off-by: Simon Trimmer <simont@opensource.cirrus.com>
Link: https://lore.kernel.org/r/20210913160057.103842-3-simont@opensource.cirrus.com


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