dt-bindings: sram: Merge Renesas SRAM bindings into generic

The Renesas SRAM bindings list only compatible so integrate them into
generic SRAM bindings schema.
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
Signed-off-by: Rob Herring <robh@kernel.org>

Documentation/devicetree/bindings/sram/renesas,smp-sram.txt

-* Renesas SMP SRAM
-
-Renesas R-Car Gen2 and RZ/G1 SoCs need a small piece of SRAM for the jump stub
-for secondary CPU bringup and CPU hotplug.
-This memory is reserved by adding a child node to a "mmio-sram" node, cfr.
-Documentation/devicetree/bindings/sram/sram.txt.
-
-Required child node properties:
-  - compatible: Must be "renesas,smp-sram",
-  - reg: Address and length of the reserved SRAM.
-    The full physical (bus) address must be aligned to a 256 KiB boundary.
-
-
-Example:
-
-	icram1:	sram@e63c0000 {
-		compatible = "mmio-sram";
-		reg = <0 0xe63c0000 0 0x1000>;
-		#address-cells = <1>;
-		#size-cells = <1>;
-		ranges = <0 0 0xe63c0000 0x1000>;
-
-		smp-sram@0 {
-			compatible = "renesas,smp-sram";
-			reg = <0 0x10>;
-		};
-	};

Documentation/devicetree/bindings/sram/sram.yaml

@@ -67,6 +67,7 @@ patternProperties:
         enum:
           - amlogic,meson8-smp-sram
           - amlogic,meson8b-smp-sram
+          - renesas,smp-sram
           - samsung,exynos4210-sysram
           - samsung,exynos4210-sysram-ns
 
@@ -185,3 +186,17 @@ examples:
             reg = <0x1ff80 0x8>;
         };
     };
+
+  - |
+    sram@e63c0000 {
+        compatible = "mmio-sram";
+        reg = <0xe63c0000 0x1000>;
+        #address-cells = <1>;
+        #size-cells = <1>;
+        ranges = <0 0xe63c0000 0x1000>;
+
+        smp-sram@0 {
+            compatible = "renesas,smp-sram";
+            reg = <0 0x10>;
+        };
+    };