dt-bindings: sram: sunxi-sram: Add D1 compatible string

D1 needs to export a register for managing some LDO regulators, so it
needs a unique compatible.

Signed-off-by: Samuel Holland <samuel@sholland.org>
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Heiko Stuebner <heiko@sntech.de>
Link: https://lore.kernel.org/r/20220815041248.53268-3-samuel@sholland.org


Signed-off-by: Jernej Skrabec <jernej.skrabec@gmail.com>