ASoC: some minor changes for AD1836 and AD1938 codec drivers

1. delete redundant assignment to bus field in spi_driver structure
2. fix lost assignment to set_bias_level entry in ad1938 codec dai
3. change spi driver name of ad1836 from "ad1836-spi" to "ad1836"

Signed-off-by: Barry Song <barry.song@analog.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
diff --git a/sound/soc/codecs/ad1836.c b/sound/soc/codecs/ad1836.c
index 01343dc..c48485f 100644
--- a/sound/soc/codecs/ad1836.c
+++ b/sound/soc/codecs/ad1836.c
@@ -251,8 +251,7 @@
 
 static struct spi_driver ad1836_spi_driver = {
 	.driver = {
-		.name	= "ad1836-spi",
-		.bus	= &spi_bus_type,
+		.name	= "ad1836",
 		.owner	= THIS_MODULE,
 	},
 	.probe		= ad1836_spi_probe,