netfilter: nf_flow_table_offload: Fix block_cb tc_setup_type as TC_SETUP_CLSFLOWER

Add/del/stats flows through block_cb call must set the tc_setup_type as
TC_SETUP_CLSFLOWER.

Fixes: c29f74e0 ("netfilter: nf_flow_table: hardware offload support")
Signed-off-by: wenxu <wenxu@ucloud.cn>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>