MSM CCI hardware monitor device

msmcci-hwmon is a device that represents the MSM CCI hardware monitors
that can be used to measure the various types of requests in the MSM CCI.

Required properties:
- compatible:		Must be "qcom,msmcci-hwmon"
- reg:			Pairs of physical base addresses and region sizes of
			memory mapped registers.
- interrupts:		Lists the threshold IRQ.
- qcom,counter-event-sel:	Array of event selection values.
- qcom,target-dev:	The DT device that is monitored by this MSM CCI
			counter configuration.

Optional properties:
- qcom,secure_io	Indicates register access are secured.
- qcom,shared-irq       Indicates ccci-hwmon counters share the interrupt.

Example:
	qcom,msmcci-hwmon {
		compatible = "qcom,msmcci-hwmon";
		reg = <0xf910f000 0xb0>,
		      <0xf910f004 0xb0>;
		interrupts = <0 345 4>,
			     <0 346 4>;
		qcom,counter-event-sel = <1 2>;
		qcom,target-dev = <&cci_cache>;
	};