usb: dwc3: fix fault at system suspend if device was already runtime suspended

In the Linux kernel, the following vulnerability has been resolved: usb: dwc3: fix fault at system suspend if device was already runtime suspended If the device was already runtime suspended then during system suspend we cannot access the device registers else it will crash. Also we cannot access any registers after dwc3_core_exit() on some platforms so move the dwc3_enable_susphy() call to the top.