ARM: dts: exynos: enable PMIC wakeup from suspend on Itop Core

The RTC on S5M8767 PMIC can wakeup the system from suspend to RAM.
Add a generic property for this.

Signed-off-by: Krzysztof Kozlowski <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]

arch/arm/boot/dts/exynos4412-itop-scp-core.dtsi

···
 						 <1025000>, <950000>,
 						 <918750>, <900000>,
 						 <875000>, <831250>;
+		wakeup-source;
 
 		regulators {
 			ldo1_reg: LDO1 {