mlxsw: spectrum: Convert ndo_setup_tc offloads to block callbacks

Benefit from the newly introduced block callback infrastructure and
convert ndo_setup_tc calls for matchall and flower offloads to block
callbacks.

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