On inserting a mdb entry, fdb_search_and_insert is used to add a port to
the qca8k target entry in the FDB db.

A FDB entry can't be modified so it needs to be removed and insert again
with the new values.

To detect if an entry already exist, the SEARCH operation is used and we
check the aging of the entry. If the entry is not 0, the entry exist and
we proceed to delete it.

Current code have 2 main problem:
- The condition to check if the FDB entry exist is wrong and should be
  the opposite.
- When a FDB entry doesn't exist, aging was never actually set to the
  STATIC value resulting in allocating an invalid entry.

Fix both problem by adding aging support to the function, calling the
function with STATIC as aging by default and finally by correct the
condition to check if the entry actually exist.

Fixes: ba8f870d ("net: dsa: qca8k: add support for mdb_add/del")
Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>
Cc: stable@vger.kernel.org
Signed-off-by: David S. Miller <davem@davemloft.net>