ASoC: Make snd_soc_dapm_kcontrol_codec() inline

snd_soc_dapm_kcontrol_codec() is a extremely simple function and inlining it
typically results in less code than necessary for calling the non-inlined
version of the function.

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