dt-bindings: sram: sunxi: Add compatible for the A64 SRAM C1

This introduces a new compatible for the A64 SRAM C1 section, that is
compatible with the SRAM C1 section as found on the A10.

Signed-off-by: Paul Kocialkowski <paul.kocialkowski@bootlin.com>
Acked-by: Chen-Yu Tsai <wens@csie.org>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>