ARM: dts: add syscon compatible string for AP syscon

This syscon needs to be looked up by clocks, flash protection
and other consumers.
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

arch/arm/boot/dts/integratorap.dts

@@ -42,7 +42,7 @@ uartclk: uartclk@14.74M {
 	};
 
 	syscon {
-		compatible = "arm,integrator-ap-syscon";
+		compatible = "arm,integrator-ap-syscon", "syscon";
 		reg = <0x11000000 0x100>;
 		interrupt-parent = <&pic>;
 		/* These are the logical module IRQs */