rocker: move dereference before free

My static checker complains that ofdpa_neigh_del() can sometimes free
"found".   It just makes sense to use it first before deleting it.

Fixes: ecf244f7

 ("rocker: fix maybe-uninitialized warning")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>