dt-bindings: sram: Add compatible strings for the Meson AO ARC SRAM

Amlogic Meson8, Meson8b and Meson8m2 SoCs embed an ARC EM4 core
typically used for managing system suspend. A section of the SoCs SRAM
is mapped as memory for this ARC core. Add new compatible strings for
the SRAM section for the ARC core memory.

Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Kevin Hilman <khilman@baylibre.com>
Link: https://lore.kernel.org/r/20210102205904.2691120-2-martin.blumenstingl@googlemail.com