thunderbolt: No need to take tb->lock in domain suspend/complete

If the connection manager implementation needs to touch the domain
structures it ought to take the lock itself. Currently only ICM
implements these hooks and it does not need the lock because we there
will be no notifications before driver ready message is sent to it.

Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>