media: pvrusb2: fix URB leak in pvr2_send_request_ex

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.

Reported-by: syzbot+405dcd13121ff75a9e16@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=405dcd13121ff75a9e16
Signed-off-by: Szymon Wilczek <szymonwilczek@gmx.com>
Acked-by: Mike Isely <isely@pobox.com>
Signed-off-by: Hans Verkuil <hverkuil+cisco@kernel.org>