Spreadtrum timers

The Spreadtrum SC9860 platform provides 3 general-purpose timers.
These timers can support 32bit or 64bit counter, as well as supporting
period mode or one-shot mode, and they are can be wakeup source
during deep sleep.

Required properties:
- compatible: should be "sprd,sc9860-timer" for SC9860 platform.
- reg: The register address of the timer device.
- interrupts: Should contain the interrupt for the timer device.
- clocks: The phandle to the source clock (usually a 32.768 KHz fixed clock).

Example:
	timer@40050000 {
		compatible = "sprd,sc9860-timer";
		reg = <0 0x40050000 0 0x20>;
		interrupts = <GIC_SPI 26 IRQ_TYPE_LEVEL_HIGH>;
		clocks = <&ext_32k>;
	};