Additionally it looks like rtud entries where wrong previously from some moment
because entries had wrong destination port (reported by rtu_stat).
However no switch missbehaviour was observed.
As a side effect rtud removes entries after cable unplug.

Requires commits:
-- "userspace/libwr: shmem init-time lock"
-- "userspace/wrsw_hal: add support for shmem init-time lock"

Signed-off-by: Adam Wujek <adam.wujek@cern.ch>