ARM: tegra: apalis: Add digital audio pin muxing

Add Apalis digital audio pin muxing which is e.g. used for HDA operation
together with the Realtek HDA codec as found on the Apalis Evaluation
board.

Signed-off-by: Marcel Ziswiler <marcel.ziswiler@toradex.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>