dt-bindings: clk: meson: add g12a periph clock controller bindings

Add new clock controller compatible and dt-bindings header for the
Everything-Else domain of the g12a SoC

Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Jian Hu <jian.hu@amlogic.com>
Signed-off-by: Jerome Brunet <jbrunet@baylibre.com>
Reviewed-by: Neil Armstrong <narmstrong@baylibre.com>
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Link: https://lkml.kernel.org/r/20190201145345.6795-3-jbrunet@baylibre.com