selftests: mptcp: fix wait_rm_addr/sf parameters

The second input parameter of 'wait_rm_addr/sf $1 1' is misused. If it's
1, wait_rm_addr/sf will never break, and will loop ten times, then
'wait_rm_addr/sf' equals to 'sleep 1'. This delay time is too long,
which can sometimes make the tests fail.

A better way to use wait_rm_addr/sf is to use rm_addr/sf_count to obtain
the current value, and then pass into wait_rm_addr/sf.

Fixes: 4369c198 ("selftests: mptcp: test userspace pm out of transfer")
Cc: stable@vger.kernel.org
Suggested-by: Matthieu Baerts <matttbe@kernel.org>
Reviewed-by: Matthieu Baerts <matttbe@kernel.org>
Signed-off-by: Geliang Tang <geliang.tang@suse.com>
Signed-off-by: Mat Martineau <martineau@kernel.org>
Link: https://lore.kernel.org/r/20231025-send-net-next-20231025-v1-2-db8f25f798eb@kernel.org


Signed-off-by: Jakub Kicinski <kuba@kernel.org>