ARM: dts: sun4i: Add A10 SRAM and SRAM controller

The A10 has a few SRAM that can be mapped either to a device or to the CPU,
with the mapping being controlled by a SRAM controller.

Since most of the time these SRAM won't be accessible by the CPU,
we can't use the mmio-sram driver and compatible.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>