Fix the sparse warning about a context imbalance in the
sfw_deactivate_session function by telling sparse that it
should expect the lock to be held on entry and held on exit.

  drivers/staging/lustre/lnet/selftest/framework.c:210:9: warning: context imbalance in 'sfw_deactivate_session' - unexpected unlock
Signed-off-by: Jeremiah Mahler <jmmahler@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>