usb: dwc2: pci: Handle error cleanup in probe

The probe function doesn't properly handle errors. Fix it so that it
properly handles cleanup.

Acked-by: John Youn <johnyoun@synopsys.com>
Signed-off-by: Vardan Mikayelyan <mvardan@synopsys.com>
Signed-off-by: John Youn <johnyoun@synopsys.com>
Signed-off-by: Grigor Tovmasyan <tovmasya@synopsys.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>