Documentation: Propagate pm_snoc_client documentation to msm-3.18

* MSM PM SNOC client

MSM PM SNOC client device is used to setup a bus request for 100 Mhz for the

SNOC bus when the Apps cores are active. This bus request helps mitigate the

exit latency from power collapse in cases where there aren't any active bus

requests for SNOC.

This device is dependent on the pm-8x60 device, which configures the low power

mode of respective cores.

The required properties of this device are:

- compatible: qcom,pm-snoc-client

- qcom,msm-bus,name:            String representing the client-name

- qcom,msm-bus,num-cases:       Total number of usecases

- qcom,msm-bus,active-only:     Boolean context flag for requests in active or

                                dual (active & sleep) contex

- qcom,msm-bus,num-paths:       Total number of master-slave pairs

- qcom,msm-bus,vectors-KBps:    Arrays of unsigned integers representing:

                                master-id, slave-id, arbitrated bandwidth

                                in KBps, instantaneous bandwidth in KBps

Example:

	qcom,pm-snoc-client {

		compatible = "qcom,pm-snoc-client";

		qcom,msm-bus,name = "ocimem_snoc";

		qcom,msm-bus,num-cases = <2>;

		qcom,msm-bus,active-only;

		qcom,msm-bus,num-paths = <1>;

		qcom,msm-bus,vectors =

			<22 512 0 0>,

			<22 512 320000 3200000>;

	};