mptcp: use sock_kfree_s instead of kfree

mptcp: use sock_kfree_s instead of kfree

The local address entries on userspace_pm_local_addr_list are allocated
by sock_kmalloc().

It's then required to use sock_kfree_s() instead of kfree() to free
these entries in order to adjust the allocated size on the sk side.

Fixes: 24430f8bf516 ("mptcp: add address into userspace pm list")
Cc: stable@vger.kernel.org
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>
Link: https://patch.msgid.link/20241104-net-mptcp-misc-6-12-v1-2-c13f2ff1656f@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>