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.