dwc2: gadget: Fix completed transfer size calculation in DDMA

Fix calculation of transfer size on completion in function
dwc2_gadget_get_xfersize_ddma().

Added increment of descriptor pointer to move to next descriptor in
the loop.

Fixes: aa3e8bc8 ("usb: dwc2: gadget: DDMA transfer start and complete")
Signed-off-by: NMinas Harutyunyan <hminas@synopsys.com>
Signed-off-by: NFelipe Balbi <felipe.balbi@linux.intel.com>

drivers/usb/dwc2/gadget.c

@@ -2325,6 +2325,7 @@ static unsigned int dwc2_gadget_get_xfersize_ddma(struct dwc2_hsotg_ep *hs_ep)
 		if (status & DEV_DMA_STS_MASK)
 			dev_err(hsotg->dev, "descriptor %d closed with %x\n",
 				i, status & DEV_DMA_STS_MASK);
+		desc++;
 	}
 
 	return bytes_rem;