ARM: dts: sun7i: Add A20 SRAM and SRAM controller

The A20 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: Maxime Ripard <maxime.ripard@free-electrons.com>
[hdegoede@redhat.com: Do not change soc node name, change compatible to
 sun4i-a10-sram-controller to match the driver change]
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>

arch/arm/boot/dts/sun7i-a20.dtsi

@@ -521,12 +521,46 @@ clk_out_b: clk@01c201f4 {
 		};
 	};
 
+	/*
+	 * Note we use the address where the mmio registers start, not where
+	 * the SRAM blocks start, this cannot be changed because that would be
+	 * a devicetree ABI change.
+	 */
 	soc@01c00000 {
 		compatible = "simple-bus";
 		#address-cells = <1>;
 		#size-cells = <1>;
 		ranges;
 
+		sram@00000000 {
+			compatible = "allwinner,sun4i-a10-sram";
+			reg = <0x00000000 0x4000>;
+			allwinner,sram-name = "A1";
+		};
+
+		sram@00004000 {
+			compatible = "allwinner,sun4i-a10-sram";
+			reg = <0x00004000 0x4000>;
+			allwinner,sram-name = "A2";
+		};
+
+		sram@00008000 {
+			compatible = "allwinner,sun4i-a10-sram";
+			reg = <0x00008000 0x4000>;
+			allwinner,sram-name = "A3-A4";
+		};
+
+		sram@00010000 {
+			compatible = "allwinner,sun4i-a10-sram";
+			reg = <0x00010000 0x1000>;
+			allwinner,sram-name = "D";
+		};
+
+		sram-controller@01c00000 {
+			compatible = "allwinner,sun4i-a10-sram-controller";
+			reg = <0x01c00000 0x30>;
+		};
+
 		nmi_intc: interrupt-controller@01c00030 {
 			compatible = "allwinner,sun7i-a20-sc-nmi";
 			interrupt-controller;