ASoC: cs35l32: Add bindings for CS35L32

The patch adds device tree bindings file for the Cirrus Logic CS35L32
Signed-off-by: Brian Austin <brian.austin@cirrus.com>
Signed-off-by: Mark Brown <broonie@linaro.org>

Documentation/devicetree/bindings/sound/cs35l32.txt

+CS35L32 audio CODEC
+
+Required properties:
+
+  - compatible : "cirrus,cs35l32"
+
+  - reg : the I2C address of the device for I2C. Address is determined by the level
+  of the AD0 pin. Level 0 is 0x40 while Level 1 is 0x41.
+
+  - VA-supply, VP-supply : power supplies for the device,
+  as covered in Documentation/devicetree/bindings/regulator/regulator.txt.
+
+Optional properties:
+
+  - reset-gpios : a GPIO spec for the reset pin. If specified, it will be
+  deasserted before communication to the codec starts.
+
+  - cirrus,boost-manager : Boost voltage control.
+  0 = Automatically managed.  Boost-converter output voltage is the higher
+  of the two: Class G or adaptive LED voltage.
+  1 = Automatically managed irrespective of audio, adapting for low-power
+  dissipation when LEDs are ON, and operating in Fixed-Boost Bypass Mode
+  if LEDs are OFF (VBST = VP).
+  2 = (Default) Boost voltage fixed in Bypass Mode (VBST = VP).
+  3 = Boost voltage fixed at 5 V.
+
+  - cirrus,sdout-datacfg : Data configuration for dual CS35L32 applications only.
+  Determines the data packed in a two-CS35L32 configuration.
+  0 = Left/right channels VMON[11:0], IMON[11:0], VPMON[7:0].
+  1 = Left/right channels VMON[11:0], IMON[11:0], STATUS.
+  2 = (Default) left/right channels VMON[15:0], IMON [15:0].
+  3 = Left/right channels VPMON[7:0], STATUS.
+
+  - cirrus,sdout-share : SDOUT sharing. Determines whether one or two CS35L32
+  devices are on board sharing SDOUT.
+  0 = (Default) One IC.
+  1 = Two IC's.
+
+  - cirrus,battery-recovery : Low battery nominal recovery threshold, rising VP.
+  0 = 3.1V
+  1 = 3.2V
+  2 = 3.3V (Default)
+  3 = 3.4V
+
+  - cirrus,battery-threshold : Low battery nominal threshold, falling VP.
+  0 = 3.1V
+  1 = 3.2V
+  2 = 3.3V
+  3 = 3.4V (Default)
+  4 = 3.5V
+  5 = 3.6V
+
+Example:
+
+codec: codec@40 {
+	compatible = "cirrus,cs35l32";
+	reg = <0x40>;
+	reset-gpios = <&gpio 10 0>;
+	cirrus,boost-manager = <0x03>;
+	cirrus,sdout-datacfg = <0x02>;
+	VA-supply = <&reg_audio>;
+};