dt-bindings: arm: sunxi: Add several MBUS compatibles

All of the sunxi SoCs since at least the A33 have a similar structure
for the MBUS and DRAM controller, but they all have minor differences in
MBUS port assignments and DRAM controller behavior. Give each SoC its
own compatible.

Signed-off-by: Samuel Holland <samuel@sholland.org>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Jernej Skrabec <jernej.skrabec@gmail.com>
Link: https://lore.kernel.org/r/20220702042447.26734-2-samuel@sholland.org