media: pvrusb2: fix URB leak in pvr2_send_request_ex

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

media: pvrusb2: fix URB leak in pvr2_send_request_ex

When pvr2_send_request_ex() submits a write URB successfully but fails to

submit the read URB (e.g. returns -ENOMEM), it returns immediately without

waiting for the write URB to complete. Since the driver reuses the same

URB structure, a subsequent call to pvr2_send_request_ex() attempts to

submit the still-active write URB, triggering a 'URB submitted while

active' warning in usb_submit_urb().

Fix this by ensuring the write URB is unlinked and waited upon if the read

URB submission fails.