selftests: mptcp: connect: fix comment typo

Spell "transmissions" properly.

Found by searching for keyword "tranm".

Reviewed-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: Yueh-Shun Li <shamrocklee@posteo.net>
Signed-off-by: Mat Martineau <martineau@kernel.org>
Link: https://lore.kernel.org/r/20230623-send-net-next-20230623-v1-8-a883213c8ba9@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Author: ShamrockLee

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

@@ -809,7 +809,7 @@ run_tests_disconnect()
 
 	cat $cin $cin $cin > "$cin".disconnect
 
-	# force do_transfer to cope with the multiple tranmissions
+	# force do_transfer to cope with the multiple transmissions
 	sin="$cin.disconnect"
 	cin="$cin.disconnect"
 	cin_disconnect="$old_cin"