ARM: ux500: Enable the AB8500 RTC for all DT:ed DB8500 based devices

Here we add a node for the AB8500 Real Time Clock in all devices
supporting the DB8500. The AB8500 RTC driver makes use of named
interrupts we provide support for this too.
Acked-by: NLinus Walleij <linus.walleij@linaro.org>
Signed-off-by: NLee Jones <lee.jones@linaro.org>

arch/arm/boot/dts/db8500.dtsi

@@ -315,6 +315,13 @@
 				interrupt-controller;
 				#interrupt-cells = <2>;
 
+				ab8500-rtc {
+					compatible = "stericsson,ab8500-rtc";
+					interrupts = <17 0x4
+					              18 0x4>;
+					interrupt-names = "60S", "ALARM";
+				};
+
 				ab8500-gpadc {
 					compatible = "stericsson,ab8500-gpadc";
 					interrupts = <32 0x4