ASoC: sunxi: Add bindings for A23/A33/H3 codec's analog path controls

The internal codec on A23/A33/H3 is split into 2 parts. The
analog path controls are routed through an embedded custom register
bus accessed through the PRCM block.

The SoCs share a common set of inputs, outputs, and audio paths.
The following table lists the differences.

    ----------------------------------------
    | Feature \ SoC |  A23  |  A33  |  H3  |
    ----------------------------------------
    | Headphone     |   v   |   v   |      |
    ----------------------------------------
    | Line Out      |       |       |  v   |
    ----------------------------------------
    | Phone In/Out  |   v   |   v   |      |
    ----------------------------------------

Add a binding for this hardware.

Signed-off-by: Chen-Yu Tsai <wens@csie.org>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Mark Brown <broonie@kernel.org>