dt-bindings: arm: amlogic: add fbx8am binding

Add binding for the Amlogic Meson G12A-based Freebox Pop (fbx8am).

Acked-by: Conor Dooley <conor.dooley@microchip.com>
Signed-off-by: Marc Gonzalez <mgonzalez@freebox.fr>
Link: https://lore.kernel.org/r/5f238367-57f2-404e-b5ce-521c389bc728@freebox.fr


Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>