usb: image: mdc800: kill download URB on timeout

In the Linux kernel, the following vulnerability has been resolved:

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")