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

Add RAM controller and RAM PHY controller DT bindings.

Signed-off-by: Claudiu Beznea <[e-mail]>
Acked-by: Rob Herring <[e-mail]>
Signed-off-by: Nicolas Ferre <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]

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

···
 			"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:
···
 		compatible = "atmel,at91sam9g45-ddramc";
 		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