selftests: mptcp: diag: return KSFT_FAIL not test_cnt

The test counter 'test_cnt' should not be returned in diag.sh, e.g. what
if only the 4th test fail? Will do 'exit 4' which is 'exit ${KSFT_SKIP}',
the whole test will be marked as skipped instead of 'failed'!

So we should do ret=${KSFT_FAIL} instead.

Fixes: df62f2e ("selftests/mptcp: add diag interface tests")
Cc: stable@vger.kernel.org
Fixes: 42fb6cd ("selftests: mptcp: more stable diag tests")
Signed-off-by: Geliang Tang <tanggeliang@kylinos.cn>
Reviewed-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

Author: Geliang Tang

tools/testing/selftests/net/mptcp/diag.sh

@@ -69,7 +69,7 @@ __chk_nr()
 		else
 			echo "[ fail ] expected $expected found $nr"
 			mptcp_lib_result_fail "${msg}"
-			ret=$test_cnt
+			ret=${KSFT_FAIL}
 		fi
 	else
 		echo "[  ok  ]"
@@ -124,11 +124,11 @@ wait_msk_nr()
 	if [ $i -ge $timeout ]; then
 		echo "[ fail ] timeout while expecting $expected max $max last $nr"
 		mptcp_lib_result_fail "${msg} # timeout"
-		ret=$test_cnt
+		ret=${KSFT_FAIL}
 	elif [ $nr != $expected ]; then
 		echo "[ fail ] expected $expected found $nr"
 		mptcp_lib_result_fail "${msg} # unexpected result"
-		ret=$test_cnt
+		ret=${KSFT_FAIL}
 	else
 		echo "[  ok  ]"
 		mptcp_lib_result_pass "${msg}"