sctp: Use sctp_clone_sock() in sctp_do_peeloff().

sctp: Use sctp_clone_sock() in sctp_do_peeloff().

sctp_do_peeloff() calls sock_create() to allocate and initialise
struct sock, inet_sock, and sctp_sock, but later sctp_copy_sock()
and sctp_sock_migrate() overwrite most fields.

What sctp_do_peeloff() does is more like accept().

Let's use sock_create_lite() and sctp_clone_sock().

Signed-off-by: Kuniyuki Iwashima <kuniyu@google.com>
Acked-by: Xin Long <lucien.xin@gmail.com>
Link: https://patch.msgid.link/20251023231751.4168390-8-kuniyu@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>