Add codec registration specific function in preparation
for DAI-multicodec support.

No functional change.
Signed-off-by: NMisael Lopez Cruz <misael.lopez@ti.com>
[fparent@baylibre.com: Adapt to 3.14+]
Signed-off-by: NFabien Parent <fparent@baylibre.com>
Signed-off-by: NBenoit Cousson <bcousson@baylibre.com>
Signed-off-by: NMark Brown <broonie@linaro.org>