usb: gadget: f_dfu: write req->actual bytes

If last packet is short, we shouldn't write req->length bytes to
non-volatile media, we should write only what's available to us, which
is held in req->actual.

Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

drivers/usb/gadget/f_dfu.c

@@ -159,7 +159,7 @@ static void dnload_request_complete(struct usb_ep *ep, struct usb_request *req)
 	int ret;
 
 	ret = dfu_write(dfu_get_entity(f_dfu->altsetting), req->buf,
-			req->length, f_dfu->blk_seq_num);
+			req->actual, f_dfu->blk_seq_num);
 	if (ret) {
 		f_dfu->dfu_status = DFU_STATUS_errUNKNOWN;
 		f_dfu->dfu_state = DFU_STATE_dfuERROR;