ASoC: tlv320aic31xx: add explicit support for tlv320dac31xx

tlv320dac31xx is a subset of tlv320aic31xx:
- it does not have MIC inputs and ADC, thus capture is not supported,
- it has analog inputs AIN1/AIN2 that can be mixed into output.

Although tlv320dac31xx does work with tlv320aic31xx driver, this setup
does register non-existent widgets and non-existent capture stream.
Thus userspace lists non-existent objects in user interfaces, an can
access these, causing operations with device registers that are
declared as "reserved" in tlv320dac31xx datasheet.

This patch fixes this situation by separating controls/widgets/routes
into common, aic31xx-specific, and dac31xx-specific parts. Only parts
that match actual hardware (as declared in "compatible" device tree
property) are registered.

Changes from v1:
- update device tree binding documentation,
- rebased on top of "ASoC: codec duplicated callback function goes to
  component on tlv320aic31xx" commit.
Signed-off-by: Nikita Yushchenko <nikita.yoush@cogentembedded.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

Documentation/devicetree/bindings/sound/tlv320aic31xx.txt

@@ -11,6 +11,7 @@ Required properties:
     "ti,tlv320aic3110" - TLV320AIC3110 (stereo speaker amp, no MiniDSP)
     "ti,tlv320aic3120" - TLV320AIC3120 (mono speaker amp, MiniDSP)
     "ti,tlv320aic3111" - TLV320AIC3111 (stereo speaker amp, MiniDSP)
+    "ti,tlv320dac3100" - TLV320DAC3100 (no ADC, mono speaker amp, no MiniDSP)
 
 - reg - <int> -  I2C slave address
 - HPVDD-supply, SPRVDD-supply, SPLVDD-supply, AVDD-supply, IOVDD-supply,
@@ -37,9 +38,11 @@ CODEC output pins:
   * MICBIAS
 
 CODEC input pins:
-  * MIC1LP
-  * MIC1RP
-  * MIC1LM
+  * MIC1LP, devices with ADC
+  * MIC1RP, devices with ADC
+  * MIC1LM, devices with ADC
+  * AIN1, devices without ADC
+  * AIN2, devices without ADC
 
 The pins can be used in referring sound node's audio-routing property.
 

sound/soc/codecs/tlv320aic31xx.h

@@ -24,12 +24,14 @@
 
 #define AIC31XX_STEREO_CLASS_D_BIT	0x1
 #define AIC31XX_MINIDSP_BIT		0x2
+#define DAC31XX_BIT			0x4
 
 enum aic31xx_type {
 	AIC3100	= 0,
 	AIC3110 = AIC31XX_STEREO_CLASS_D_BIT,
 	AIC3120 = AIC31XX_MINIDSP_BIT,
 	AIC3111 = (AIC31XX_STEREO_CLASS_D_BIT | AIC31XX_MINIDSP_BIT),
+	DAC3100 = DAC31XX_BIT,
 };
 
 struct aic31xx_pdata {