selftests: Set default protocol for raw sockets in nettest

IPPROTO_IP (0) is not valid for raw sockets. Default the protocol for
raw sockets to IPPROTO_RAW if the protocol has not been set via the -P
option.
Signed-off-by: David Ahern <dsahern@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

tools/testing/selftests/net/nettest.c

@@ -1667,6 +1667,8 @@ int main(int argc, char *argv[])
 		case 'R':
 			args.type = SOCK_RAW;
 			args.port = 0;
+			if (!args.protocol)
+				args.protocol = IPPROTO_RAW;
 			break;
 		case 'P':
 			pe = getprotobyname(optarg);