Fix checkpatch.pl CHECK as follows:
CHECK: spinlock_t definition without comment
+       spinlock_t xfer_lock;
Signed-off-by: Bitan Biswas <bbiswas@nvidia.com>
Reviewed-by: Dmitry Osipenko <digetx@gmail.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>