ASoC: codecs: Remove rtd->codec usage from CODEC drivers

In order to support CODEC<->CODEC links remove the assumption that there
is only a single CODEC on a DAI link by removing the use of the CODEC
pointer in the rtd from the CODEC drivers. They are already being passed
their DAI whenever they are passed an rtd and can get the CODEC from
there.

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
diff --git a/sound/soc/codecs/ad1836.c b/sound/soc/codecs/ad1836.c
index 12e3b41..c67b50d 100644
--- a/sound/soc/codecs/ad1836.c
+++ b/sound/soc/codecs/ad1836.c
@@ -162,9 +162,7 @@
 		struct snd_soc_dai *dai)
 {
 	int word_len = 0;
-
-	struct snd_soc_pcm_runtime *rtd = substream->private_data;
-	struct snd_soc_codec *codec = rtd->codec;
+	struct snd_soc_codec *codec = dai->codec;
 
 	/* bit size */
 	switch (params_format(params)) {