selftests: bpf: fix -Wformat-security warning for flow_dissector_load.c

flow_dissector_load.c:55:19: warning: format string is not a string literal (potentially insecure)
      [-Wformat-security]
                error(1, errno, command);
                                ^~~~~~~
flow_dissector_load.c:55:19: note: treat the string as an argument to avoid this
                error(1, errno, command);
                                ^
                                "%s",
1 warning generated.
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

tools/testing/selftests/bpf/flow_dissector_load.c

@@ -52,7 +52,7 @@ static void detach_program(void)
 	sprintf(command, "rm -r %s", cfg_pin_path);
 	ret = system(command);
 	if (ret)
-		error(1, errno, command);
+		error(1, errno, "%s", command);
 }
 
 static void parse_opts(int argc, char **argv)