bpf: samples/sockmap detach sock ops program

samples/sockops program keeps the sock_ops program attached to cgroup.
Fixed this by detaching program before exit.

Signed-off-by: Prashant Bhole <bhole_prashant_q7@lab.ntt.co.jp>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

samples/sockmap/sockmap_user.c

@@ -566,6 +566,7 @@ run:
 	else
 		fprintf(stderr, "unknown test\n");
 out:
+	bpf_prog_detach2(prog_fd[2], cg_fd, BPF_CGROUP_SOCK_OPS);
 	close(s1);
 	close(s2);
 	close(p1);