dt-bindings: atmel-sysreg: add bindings for sama7g5

Add RAM controller and RAM PHY controller DT bindings.
Signed-off-by: Claudiu Beznea <claudiu.beznea@microchip.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Nicolas Ferre <nicolas.ferre@microchip.com>
Link: https://lore.kernel.org/r/20210415105010.569620-17-claudiu.beznea@microchip.com

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

@@ -45,7 +45,8 @@ RAMC SDRAM/DDR Controller required properties:
 			"atmel,at91sam9260-sdramc",
 			"atmel,at91sam9g45-ddramc",
 			"atmel,sama5d3-ddramc",
-			"microchip,sam9x60-ddramc"
+			"microchip,sam9x60-ddramc",
+			"microchip,sama7g5-uddrc"
 - reg: Should contain registers location and length
 
 Examples:
@@ -55,6 +56,17 @@ Examples:
 		reg = <0xffffe800 0x200>;
 	};
 
+RAMC PHY Controller required properties:
+- compatible: Should be "microchip,sama7g5-ddr3phy", "syscon"
+- reg: Should contain registers location and length
+
+Example:
+
+	ddr3phy: ddr3phy@e3804000 {
+		compatible = "microchip,sama7g5-ddr3phy", "syscon";
+		reg = <0xe3804000 0x1000>;
+};
+
 SHDWC Shutdown Controller
 
 required properties: