net/802: fix sparse warnings: context imbalance

Impact: Attribute function with __acquires(...) resp. __releases(...).

Fix this sparse warnings:
  net/802/tr.c:492:21: warning: context imbalance in 'rif_seq_start' - wrong count at exit
  net/802/tr.c:519:13: warning: context imbalance in 'rif_seq_stop' - unexpected unlock

Signed-off-by: Hannes Eder <hannes@hanneseder.net>
Signed-off-by: David S. Miller <davem@davemloft.net>