QCT Gunyah Hypervisor Doorbell Test Driver

The Gunyah Hypervisor Test Driver is used to validate gunyah hypervisor
functionality. It includes test node for gunyah doorbell for vms.

Required properties:
- compatible:	"qcom,gh-dbl"
- qcom,label:   The ID of doorbell which is define in gh_dbl.h

Example:

		qcom,test-dbl {
			compatible = "qcom,gh-dbl";
			qcom,label = <0x4>;
		};