bindings: Add dt-bindings for pdc controller on qc SoCs

QTI PDC interrupt controller

PDC is QTI's platform parent interrupt controller that serves as wakeup source.

Newer QTI SOCs are replacing MPM (MSM sleep Power Manager) with PDC (Power

Domain Controller) to manage subsystem wakeups and resources during sleep.

This driver marks the wakeup interrupts in APSS PDC such that it monitors the

interrupts when the system is asleep, wakes up the APSS when one of these

interrupts occur and replays it to the subsystem interrupt controller after it

becomes operational.

Earlier MPM architecture used arch-extension of GIC interrupt

controller to mark enabled wake-up interrupts and monitor these when the

system goes to sleep. Since the arch-extensions are no-longer available

on newer kernel versions, this driver is implemented as hierarchical irq

domain.  GIC is parent interrupt controller at the highest level.

Platform interrupt controller PDC is next in hierarchy, followed by others.

This driver only configures the interrupts, does not handle them.

PDC interrupt configuration involves programming of 2 set of registers:

IRQ_ENABLE_BANK    - Enable the irq

IRQ_i_CFG          - Configure the interrupt i

Properties:

- compatible:

	Usage: required

	Value type: <string>

	Definition: Should contain one of -

		    "qcom,pdc-sdm845",

		    "qcom,pdc-sdmmagpie",

		    "qcom,pdc-sm6150",

	            "qcom,pdc-sm8150",

		    "qcom,pdc-sdxprairie",

	            "qcom,pdc-atoll"

- reg:

	Usage: required

	Value type: <prop-encoded-array>

	Definition: Specifies the base physical address for PDC hardware

			block for DRV2.

- interrupt-cells:

	Usage: required

	Value type: <u32>

	Definition: Specifies the number of cells needed to encode an interrupt source.

			Value must be 3.

			The encoding of these cells are same as described in

			Documentation/devicetree/bindings/interrupt-controller/arm,gic-v3.txt

- interrupt-parent:

	Usage: required

	Value type: <phandle>

	Definition: Specifies the interrupt parent necessary for hierarchical domain to operate.

- interrupt-controller:

	Usage: required

	Value type: <bool>

	Definition: Identifies the node as an interrupt controller.

Example:

pdcgic: interrupt-controller@0xb220000{

	compatible = "qcom,pdc-sdm845";

	reg = <0xb220000 0x30000>;

	#interrupt-cells = <3>;

	interrupt-parent = <&intc>;

	interrupt-controller;

};