mlxsw: spectrum: acl: Remove mlxsw_afk_encode() block range args and key/mask check

Since two remaining users of mlxsw_afk_encode() do not specify
block ranges to work on, remove the args. Also, key/mask is always
non-NULL now, so skip the checks.

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