ARM: dts: am334x: pdu001: Use correct node name for RTC

RTC devices should be named "rtc" according to the standard RTC device
tree schema.
Signed-off-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>

arch/arm/boot/dts/am335x-pdu001.dts

@@ -353,7 +353,7 @@ tft-panel@0 {
 		};
 	};
 
-	mcp79400: mcp79400@6f {
+	mcp79400: rtc@6f {
 		compatible = "microchip,mcp7940x";
 		reg = <0x6f>;
 	};