ARM: dts: at91: sama5d4: add labels to soc dtsi for derivative boards

This adds labels to commonly used device-tree nodes so that derivative
boards can avoid ahb/apb hierarchy.

Signed-off-by: Eugen Hristev <[e-mail]>
Acked-by: Ludovic Desroches <[e-mail]>
Signed-off-by: Alexandre Belloni <[e-mail]>

arch/arm/boot/dts/sama5d4.dtsi

···
 				};
 			};
 
-			rstc@fc068600 {
+			reset_controller: rstc@fc068600 {
 				compatible = "atmel,sama5d3-rstc", "atmel,at91sam9g45-rstc";
 				reg = <0xfc068600 0x10>;
 				clocks = <&clk32k>;
 			};
 
-			shdwc@fc068610 {
+			shutdown_controller: shdwc@fc068610 {
 				compatible = "atmel,at91sam9x5-shdwc";
 				reg = <0xfc068610 0x10>;
 				clocks = <&clk32k>;
···
 				clocks = <&h32ck>;
 			};
 
-			watchdog@fc068640 {
+			watchdog: watchdog@fc068640 {
 				compatible = "atmel,sama5d4-wdt";
 				reg = <0xfc068640 0x10>;
 				interrupts = <4 IRQ_TYPE_LEVEL_HIGH 7>;
···
 			};
 
 
-			pinctrl@fc06a000 {
+			pinctrl: pinctrl@fc06a000 {
 				#address-cells = <1>;
 				#size-cells = <1>;
 				compatible = "atmel,sama5d3-pinctrl", "atmel,at91sam9x5-pinctrl", "simple-bus";