Use mptcp_lib_print_ok() and _err() helpers in script simult_flows.sh
to print test results with colors.

Having colors helps to quickly identify issues when looking at a long
list of output logs and results.

Signed-off-by: Geliang Tang <geliang.tang@linux.dev>
---
 tools/testing/selftests/net/mptcp/simult_flows.sh | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/tools/testing/selftests/net/mptcp/simult_flows.sh b/tools/testing/selftests/net/mptcp/simult_flows.sh
index 57180c2da605..c077e05e1319 100755
--- a/tools/testing/selftests/net/mptcp/simult_flows.sh
+++ b/tools/testing/selftests/net/mptcp/simult_flows.sh
@@ -169,12 +169,12 @@ do_transfer()
 	printf "%-16s" " max $max_time "
 	if [ $retc -eq 0 ] && [ $rets -eq 0 ] && \
 	   [ $cmpc -eq 0 ] && [ $cmps -eq 0 ]; then
-		echo "[ OK ]"
+		mptcp_lib_print_ok "[ OK ]"
 		cat "$capout"
 		return 0
 	fi
 
-	echo " [ FAIL ]"
+	mptcp_lib_print_err " [ FAIL ]"
 	echo "client exit code $retc, server $rets" 1>&2
 	echo -e "\nnetns ${ns3} socket stat for $port:" 1>&2
 	ip netns exec ${ns3} ss -nita 1>&2 -o "sport = :$port"
-- 
2.35.3