samples/bpf: Fix dummy program unloading for xdp_redirect samples

The xdp_redirect and xdp_redirect_map sample programs both load a dummy
program onto the egress interfaces. However, the unload code checks these
programs against the wrong id number, and thus refuses to unload them. Fix
the comparison to avoid this.

Fixes: 3b7a8ec ("samples/bpf: Check the prog id before exiting")
Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
Acked-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

samples/bpf/xdp_redirect_map_user.c

@@ -57,7 +57,7 @@ static void int_exit(int sig)
 			printf("bpf_get_link_xdp_id failed\n");
 			exit(1);
 		}
-		if (prog_id == curr_prog_id)
+		if (dummy_prog_id == curr_prog_id)
 			bpf_set_link_xdp_fd(ifindex_out, -1, xdp_flags);
 		else if (!curr_prog_id)
 			printf("couldn't find a prog id on iface OUT\n");

samples/bpf/xdp_redirect_user.c

@@ -57,7 +57,7 @@ static void int_exit(int sig)
 			printf("bpf_get_link_xdp_id failed\n");
 			exit(1);
 		}
-		if (prog_id == curr_prog_id)
+		if (dummy_prog_id == curr_prog_id)
 			bpf_set_link_xdp_fd(ifindex_out, -1, xdp_flags);
 		else if (!curr_prog_id)
 			printf("couldn't find a prog id on iface OUT\n");