osdc/Objecter: disable lockdep for double lock

osdc/Objecter: disable lockdep for double lock

There is a special case in _recalc_linger_op_target
where we lock two sessions at once to transfer an op
between them.  It is deadlock safe because it's the only
place we lock two at once, and we hold rwlock for write
while we do it.

Signed-off-by: John Spray <john.spray@redhat.com>