nodedev: Fix double unlock of the driver on udevEnumerateDevices failure
    
    Commit @4cb719b2dc moved the driver locks around since these have become
    unnecessary at spots where the code handles now self-lockable object
    list, but missed the possible double unlock if udevEnumerateDevices
    fails, because at that point the driver lock had been already dropped.
    
    Signed-off-by: Erik Skultety <eskultet@redhat.com>