The A31 SoC's codec has various inputs, outputs and microphone bias
supplies. These can be routed on the board in different ways, such as:

  - HPCOM may be connected to have the headphone DC coupled.

  - Microphones all use the MBIAS main microphone supply or one mic may
    use the HBIAS supply, which supports headset detection and buttons.

  - Line Out may be routed to an audio jack, or an onboard speaker amp
    with power controls.

Add support for specifying the audio routes in the device tree.
Signed-off-by: Chen-Yu Tsai <wens@csie.org>
Acked-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Signed-off-by: Mark Brown <broonie@kernel.org>