usb: dwc2: pci: Move usb_phy_generic_register()

Move usb_phy_generic_register() function call to the top, to simplify
error handling. If this fails we can simply return instead of cleaning
up.

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>