usb: dwc2: host: resume root hub on port connect

Once hub is runtime suspended, dwc2 must resume it
on port connect event.
Else, roothub will stay in suspended state and will
not resume transfers.

Acked-by: John Youn <johnyoun@synopsys.com>
Signed-off-by: Gregory Herrero <gregory.herrero@intel.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>