usb: dwc2: gadget: fix packet drop issue for ISOC OUT transfers

In ISOC OUT transfer, when the OUT token received while EP disabled,
we shouldn't complete a usb request. The current flow completed one
usb request, this will lead to a packet drop to function driver.

Signed-off-by: Minas Harutyunyan <hminas@synopsys.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>