dt-bindings: clk: add G12A AO Clock and Reset Bindings

Add bindings for the Amlogic G12A AO Clock and Reset controllers.

Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Acked-by: Jerome Brunet <jbrunet@baylibre.com>
Link: https://lkml.kernel.org/r/20190212162859.20743-2-narmstrong@baylibre.com