dt-bindings: sram: allwinner, sun4i-a10-system-control: Add R40 compatibles

Allwinner R40 has system controller similar to that in A10.

Add compatibles for system controller and sram c1 region.

Signed-off-by: Jernej Skrabec <jernej.skrabec@siol.net>
Signed-off-by: Maxime Ripard <maxime@cerno.tech>
Link: https://lore.kernel.org/r/20200825173523.1289379-2-jernej.skrabec@siol.net