ARM: dts: sunxi: h3/h5: Add MBUS controller node

Both, H3 and H5, contain MBUS, which is the bus used by DMA devices to
access system memory.

MBUS controller is responsible for arbitration between channels based
on set priority and can do some other things as well, like report
bandwidth used. It also maps RAM region to different address than CPU.

Acked-by: Maxime Ripard <mripard@kernel.org>
Signed-off-by: Jernej Skrabec <jernej.skrabec@siol.net>
Signed-off-by: Maxime Ripard <maxime@cerno.tech>