QTI Inter-processor communication driver binding

This binding describes the QTI Blutooth Inter-processor communication
driver, used to download firmware/patch and means to communicate and transfer
data between Bluetooth device and host subsystems.

- compatible:
	Usage: required
	Value type: <stringlist>
	Definition: must be:
		    "qcom,bt"

-firmware:
	Usage: required
	Value type: <string>
	Definition: firmware/pathc location in filesystem.

- memory-region:
	Usage: required
	Value type: <prop-encoded-array>
	Definition: handle to memory reservation for main shared memory region.

- qcom,ipc:
	Usage: required
	Value type: <prop-encoded-array>
	Definition: three entries specifying the outgoing ipc bit used for
		    signaling the remote processor
		    - phandle to a syscon node representing the apcs registers
		    - u32 representing offset to the register within the syscon
		    - u32 representing the ipc bit within the register

- interrupts:
	Usage: required
	Value type: <prop-encoded-array>
	Definition: one entry specifying the bt ipc interrupt

= EXAMPLE
The following example shows the BT Inter-processor communication driver setup
for IPQ5018.

	bt: bt@7000000 {
		compatible = "qcom,bt";
		firmware = "IPQ5018/bt.mdt";

		memory-region = <&bt_region>;

		qcom,ipc = <&apcs 8 23>;
		interrupts = <GIC_SPI 162 IRQ_TYPE_EDGE_RISING>;

		resets = <&gcc GCC_BTSS_BCR>;
		reset-names = "btss_reset";
	};