QCOM Secure Channel Manager (SCM)

Qualcomm processors include an interface to communicate to the secure firmware.
This interface allows for clients to request different types of actions.  These
can include CPU power up/down, HDCP requests, loading of firmware, and other
assorted actions.

Required properties:
- compatible: must contain one of the following:
 * "qcom,scm-apq8064"
 * "qcom,scm-apq8084"
 * "qcom,scm-ipq4019"
 * "qcom,scm-ipq8074"
 * "qcom,scm-msm8660"
 * "qcom,scm-msm8916"
 * "qcom,scm-msm8960"
 * "qcom,scm-msm8974"
 * "qcom,scm-msm8996"
 * "qcom,scm-msm8998"
 * "qcom,scm-sc7180"
 * "qcom,scm-sdm845"
 * "qcom,scm-sm8150"
 and:
 * "qcom,scm"
- clocks: Specifies clocks needed by the SCM interface, if any:
 * core clock required for "qcom,scm-apq8064", "qcom,scm-msm8660" and
   "qcom,scm-msm8960"
 * core, iface and bus clocks required for "qcom,scm-apq8084",
   "qcom,scm-msm8916" and "qcom,scm-msm8974"
- clock-names: Must contain "core" for the core clock, "iface" for the interface
  clock and "bus" for the bus clock per the requirements of the compatible.
- qcom,dload-mode: phandle to the TCSR hardware block and offset of the
		   download mode control register (optional)
- hvc-log-cmd-id: contains SCM command id to get the hypervisor diag log.
		  If not defined, default value 0x7 will be used (optional)
- smmu-state-cmd-id: contains SCM command id to get the SMMU state. If not
		     defined, default value 0x19 will be used (optional)

Example for MSM8916:

	firmware {
		scm {
			compatible = "qcom,msm8916", "qcom,scm";
			clocks = <&gcc GCC_CRYPTO_CLK> ,
				 <&gcc GCC_CRYPTO_AXI_CLK>,
				 <&gcc GCC_CRYPTO_AHB_CLK>;
			clock-names = "core", "bus", "iface";
		};
	};