ASoC: speyside: Use snd_soc_codec_get_dapm()

The dapm field of the snd_soc_codec struct is eventually going to be
removed. Replace direct access to it with snd_soc_codec_get_dapm(), which
will return the DAPM context for the CODEC.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Acked-by: Charles Keepax <ckeepax@opensource.wolfsonmicro.com>
Signed-off-by: Mark Brown <broonie@kernel.org>