names: take the registry write lock in kdbus_name_release()

Take the write lock in kdbus_name_release() instead of
kdbus_cmd_name_release() in order to reduce the lock hold time.

This change permits to convert the kdbus_bus_find_conn_by_id() call to
kdbus_conn_find_peer() since the bus lock will also be taken later in
kdbus_name_release().

Another advantage is that now kdbus_cmd_name_release() and
kdbus_name_release() have the same semantic of kdbus_cmd_name_acquire()
and kdbus_name_acquire()

Signed-off-by: Djalal Harouni <tixxdz@opendz.org>
remove no longer needed "on behalf" logic (ABI break)
Merge remote-tracking branch 'kdbus/master' into 3.14/kdbus