mlxsw: spectrum: Add support for direct rule access

Currently the ACL rules can be accessed only by hashing. In order to
dump the activity the rules are also placed in a list.

Signed-off-by: Arkadi Sharshevsky <arkadis@mellanox.com>
Reviewed-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>