ASoC: adau: Factor out shared PLL configuration code

Multiple devices from the ADAU family share the same PLL structure and
configuration register layout. Introduce a new helper module that can be
used to calculated the PLL configuration registers based on a specified
input frequency and the desired output frequency of the PLL.

The ADAU1761/ADAU1781 and ADAU1373 drivers are updated to make use of this
new helper module. But future drivers for additional devices from the ADAU
family are also expected to make use of it.

In anticipation of sharing more infrastructure code between different
devices from the ADAU family the new module is called adau-utils.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Mark Brown <broonie@kernel.org>
diff --git a/sound/soc/codecs/Kconfig b/sound/soc/codecs/Kconfig
index 4d82a58..3e21539 100644
--- a/sound/soc/codecs/Kconfig
+++ b/sound/soc/codecs/Kconfig
@@ -269,8 +269,12 @@
 config SND_SOC_AD73311
 	tristate
 
+config SND_SOC_ADAU_UTILS
+	tristate
+
 config SND_SOC_ADAU1373
 	tristate
+	select SND_SOC_ADAU_UTILS
 
 config SND_SOC_ADAU1701
 	tristate "Analog Devices ADAU1701 CODEC"
@@ -280,6 +284,7 @@
 config SND_SOC_ADAU17X1
 	tristate
 	select SND_SOC_SIGMADSP_REGMAP
+	select SND_SOC_ADAU_UTILS
 
 config SND_SOC_ADAU1761
 	tristate