ASoC: Remove snd_soc_codec dapm field

There are no more direct users of the snd_soc_codec DAPM field left. So we
can finally remove it and switch over to directly using the component DAPM
context and remove the dapm_ptr indirection.

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