Now that we have the DT validation in place, let's convert the device tree
bindings for the Amlogic G12A DWC3 Glue Bindings over to a YAML schemas,
the AXG and GXL glue bindings will be converted later.

Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Reviewed-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
[robh: drop maxItems on vbus-supply]
Signed-off-by: Rob Herring <robh@kernel.org>