ARM: dts: r8a7779: Add device node for ARM global timer

Add a device node for the global timer, which is part of the Cortex-A9
MPCore.

The global timer can serve as an accurate (4 ns) clock source for
scheduling and delay loops.
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/20191211135222.26770-4-geert+renesas@glider.be

arch/arm/boot/dts/r8a7779.dtsi

@@ -68,6 +68,14 @@ gic: interrupt-controller@f0001000 {
 		      <0xf0000100 0x100>;
 	};
 
+	timer@f0000200 {
+		compatible = "arm,cortex-a9-global-timer";
+		reg = <0xf0000200 0x100>;
+		interrupts = <GIC_PPI 11
+			(GIC_CPU_MASK_SIMPLE(4) | IRQ_TYPE_EDGE_RISING)>;
+		clocks = <&cpg_clocks R8A7779_CLK_ZS>;
+	};
+
 	timer@f0000600 {
 		compatible = "arm,cortex-a9-twd-timer";
 		reg = <0xf0000600 0x20>;