staging: dwc2: add calls to usb_hcd_link_urb_to_ep() and friends

The driver was lacking calls to usb_hcd_link_urb_to_ep(),
usb_hcd_unlink_urb_from_ep(), and usb_hcd_check_unlink_urb(). Add
those now.

Signed-off-by: Paul Zimmerman <paulz@synopsys.com>
Tested-by: Stephen Warren <swarren@wwwdotorg.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>