selftests: mptcp: userspace pm: fix printed values

In case of errors, the printed message had the expected and the seen
value inverted.

This patch simply correct the order: first the expected value, then the
one that has been seen.

Fixes: 10d4273 ("selftests: mptcp: userspace: print error details if any")
Cc: stable@vger.kernel.org
Acked-by: Geliang Tang <geliang.tang@suse.com>
Signed-off-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

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

@@ -240,7 +240,7 @@ check_expected_one()
 	fi
 
 	stdbuf -o0 -e0 printf "\tExpected value for '%s': '%s', got '%s'.\n" \
-		"${var}" "${!var}" "${!exp}"
+		"${var}" "${!exp}" "${!var}"
 	return 1
 }