ASoC: Move standard kcontrol helpers to the component level

After moving the IO layer inside ASoC to the component level we can now easily
move the standard control helpers also to the component level. This allows to
reuse the same standard helper control implementations for other components.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Mark Brown <broonie@linaro.org>