ARM: at91: declare the at91rm9200 memory controller as a syscon

The at91rm9200 memory controller is not simply an SDRAM controller. It also
controls the EBI (External Bus Interface), the SMC (Static Memory Controller)and
the Burst Flash Controller.
Signed-off-by: NAlexandre Belloni <alexandre.belloni@free-electrons.com>
Acked-by: NNicolas Ferre <nicolas.ferre@atmel.com>

Documentation/devicetree/bindings/arm/atmel-at91.txt

@@ -98,7 +98,7 @@ Example:
 	};
 
 RAMC SDRAM/DDR Controller required properties:
-- compatible: Should be "atmel,at91rm9200-sdramc",
+- compatible: Should be "atmel,at91rm9200-sdramc", "syscon"
 			"atmel,at91sam9260-sdramc",
 			"atmel,at91sam9g45-ddramc",
 			"atmel,sama5d3-ddramc",

arch/arm/boot/dts/at91rm9200.dtsi

@@ -92,7 +92,7 @@
 			};
 
 			ramc0: ramc@ffffff00 {
-				compatible = "atmel,at91rm9200-sdramc";
+				compatible = "atmel,at91rm9200-sdramc", "syscon";
 				reg = <0xffffff00 0x100>;
 			};