mlxsw: spectrum_dpipe: Fix entries dump of the adjacency table

During the dump the per netlink packet entry counter should be zeroed out
when new packet is created.

Fixes: 190d38a5 ("mlxsw: spectrum_dpipe: Add support for adjacency table dump")
Signed-off-by: Arkadi Sharshevsky <arkadis@mellanox.com>
Reported-by: David Ahern <dsahern@gmail.com>
Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>