usb: dwc2: Add dwc2_enter_hibernation(), dwc2_exit_hibernation()

These are wrapper functions which are calling device or host
enter/exit hibernation functions.

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>