drm/tegra: hdmi - calculate HDMI audio CTS/N/AVAL values

The current table-drive approach for determining the CTS/N/AVAL values
required for HDMI audio limits audio availability to a small set of pixel
clock frequencies. Allow audio in other cases by calculating the CTS and N
value dynamically.

FIXME: This stops hdmi->dvi being set to true due to audio failure, which
then enables a bunch of other code. This breaks at least some display modes.

Signed-off-by: Stephen Warren <swarren@nvidia.com>