selftests/bpf: rename test_tc_edt.bpf.c section to expose program type

The test_tc_edt BPF program uses a custom section name, which works fine
when manually loading it with tc, but prevents it from being loaded with
libbpf.

Update the program section name to "tc" to be able to manipulate it with
a libbpf-based C test.

Signed-off-by: Alexis Lothoré (eBPF Foundation) <alexis.lothore@bootlin.com>
Link: https://lore.kernel.org/r/20251128-tc_edt-v2-1-26db48373e73@bootlin.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

Author: Tropicao

tools/testing/selftests/bpf/progs/test_tc_edt.c

@@ -99,7 +99,8 @@ static inline int handle_ipv4(struct __sk_buff *skb)
 	return TC_ACT_OK;
 }
 
-SEC("cls_test") int tc_prog(struct __sk_buff *skb)
+SEC("tc")
+int tc_prog(struct __sk_buff *skb)
 {
 	if (skb->protocol == bpf_htons(ETH_P_IP))
 		return handle_ipv4(skb);

tools/testing/selftests/bpf/test_tc_edt.sh

@@ -55,7 +55,7 @@ ip -netns ${NS_DST} route add ${IP_SRC}/32  dev veth_dst
 ip netns exec ${NS_SRC} tc qdisc add dev veth_src root fq
 ip netns exec ${NS_SRC} tc qdisc add dev veth_src clsact
 ip netns exec ${NS_SRC} tc filter add dev veth_src egress \
-	bpf da obj ${BPF_FILE} sec cls_test
+	bpf da obj ${BPF_FILE} sec tc
 
 
 # start the listener