Now that we have the DT validation in place, let's convert the device tree
bindings for the Amlogic Display Controller over to YAML schemas.

The original example has a leftover "dmc" memory cell, that has been
removed in the yaml rewrite.

The port connection table has been dropped in favor of a description
of each port.
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20190808085522.21950-3-narmstrong@baylibre.com