usb: dwc3: dwc3-qcom: Find USB connector and register role switch

If registering a USB typeC connector, the connector node may not be a child
of the DWC3 QCOM device.  Utilize devcon graph search to lookup if any
remote endpoints contain the connector.  If a connector is present, the
DWC3 QCOM will register a USB role switch to receive role change events, as
well as attain a reference to the DWC3 core role switch to pass the event
down.

Signed-off-by: Wesley Cheng <wcheng@codeaurora.org>