ARM: rockchip: enable arm-global-timer

RK2928 and RK3066 contain a dw_apb timer component, while the rk3188 uses
a slightly similar but still different timer component. But all of them
support the ARM-global-timer that got added as clocksource driver recently.

So enable support for it to get a working clocksource for rk3188.
Signed-off-by: Heiko Stuebner <heiko@sntech.de>

arch/arm/boot/dts/rk3xxx.dtsi

@@ -41,6 +41,13 @@ L2: l2-cache-controller@10138000 {
 			cache-level = <2>;
 		};
 
+		global-timer@1013c200 {
+			compatible = "arm,cortex-a9-global-timer";
+			reg = <0x1013c200 0x20>;
+			interrupts = <GIC_PPI 11 0x304>;
+			clocks = <&dummy150m>;
+		};
+
 		local-timer@1013c600 {
 			compatible = "arm,cortex-a9-twd-timer";
 			reg = <0x1013c600 0x20>;

arch/arm/mach-rockchip/Kconfig

@@ -11,6 +11,8 @@ config ARCH_ROCKCHIP
 	select COMMON_CLK
 	select GENERIC_CLOCKEVENTS
 	select DW_APB_TIMER_OF
+	select ARM_GLOBAL_TIMER
+	select CLKSRC_ARM_GLOBAL_TIMER_SCHED_CLOCK
 	help
 	  Support for Rockchip's Cortex-A9 Single-to-Quad-Core-SoCs
 	  containing the RK2928, RK30xx and RK31xx series.