Audio codecs need a #sound-dai-cells property, so add one to the audio
codecs on various Tegra-based boards that don't have one.

Cc: Marcel Ziswiler <marcel.ziswiler@toradex.com>
Cc: Philippe Schenker <philippe.schenker@toradex.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>