ARM: dts: Enable PRNG module on exynos4412-trats2

Enable Pseudo Random Number Generator (PRNG) on Trats2 board. This
allows using hardware random number generator:
$ echo exynos > /sys/class/misc/hw_random/rng_current
Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>

arch/arm/boot/dts/exynos4412-trats2.dts

@@ -1234,6 +1234,10 @@ &pwm {
 	status = "okay";
 };
 
+&prng {
+	status = "okay";
+};
+
 &rtc {
 	status = "okay";
 	clocks = <&clock CLK_RTC>, <&max77686 MAX77686_CLK_AP>;