ASoC: tlv320aic32x4: Implement resistors on input pins

The input pins of the aic3204 have resistors inline with them.  The
current code assumes that you want a 10k resistor inline with your
inputs and implements it as a simple switch.  This patch creates an enum
for each pin and allows you to switch between not connected, 10k, 20k
and 40k ohm values.  This more closely models the acutal aic3204 part.

These pin settings are documented in TI's SLAA557 pages 135 and 136
(http://www.ti.com/lit/ml/slaa557/slaa557.pdf

).

Signed-off-by: Jeremy McDermond <nh6z@nh6z.net>
Signed-off-by: Mark Brown <broonie@kernel.org>