[TOKENRING]: Use interrupt-safe locking with rif_lock.

Change operations on rif_lock from spin_{un}lock_bh to
spin_{un}lock_irq{save,restore} equivalents.  Some of the
rif_lock critical sections are called from interrupt context via
tr_type_trans->tr_add_rif_info.  The TR NIC drivers call tr_type_trans
from their packet receive handlers.

Signed-off-by: Jay Vosburgh <fubar@us.ibm.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>