usb: image: mdc800: kill download URB on timeout

mdc800_device_read() submits download_urb and waits for completion.
If the timeout fires and the device has not responded, the function
returns without killing the URB, leaving it active.

A subsequent read() resubmits the same URB while it is still
in-flight, triggering the WARN in usb_submit_urb():

"URB submitted while active"

Check the return value of wait_event_timeout() and kill the URB if
it indicates timeout, ensuring the URB is complete before its status
is inspected or the URB is resubmitted.

Similar to
- commit 372c93131998 ("USB: yurex: fix control-URB timeout handling")
- commit b98d5000c505 ("media: rc: iguanair: handle timeouts")

Signed-off-by: Ziyi Guo <[e-mail]>
Cc: stable <[e-mail]>
Link: https://patch.msgid.link/[e-mail]
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/usb/image/mdc800.c

···
 					mutex_unlock(&mdc800->io_lock);
 					return len-left;
 				}
-				wait_event_timeout(mdc800->download_wait,
+				retval = wait_event_timeout(mdc800->download_wait,
 				     mdc800->downloaded,
 				     msecs_to_jiffies(TO_DOWNLOAD_GET_READY));
+				if (!retval)
+					usb_kill_urb(mdc800->download_urb);
 				mdc800->downloaded = 0;
 				if (mdc800->download_urb->status != 0)
 				{