samples/bpf: Fix a resource leak

The opened file should be closed in show_sockopts(), otherwise resource
leak will occur that this problem was discovered by reading code

Signed-off-by: Zhu Jun <[e-mail]>
Signed-off-by: Andrii Nakryiko <[e-mail]>
Link: https://lore.kernel.org/bpf/[e-mail]

samples/bpf/test_cgrp2_sock.c

···
 		return 1;
 	}
 
-	if (get_bind_to_device(sd, name, sizeof(name)) < 0)
+	if (get_bind_to_device(sd, name, sizeof(name)) < 0) {
+		close(sd);
 		return 1;
+	}
 
 	mark = get_somark(sd);
 	prio = get_priority(sd);