vsock: fold sk_acceptq_added() into vsock_add_pending()

vsock: fold sk_acceptq_added() into vsock_add_pending()

Move sk_acceptq_added() into vsock_add_pending() so callers cannot
forget it. vmci is the only transport using the pending list and
is updated accordingly.

Suggested-by: Stefano Garzarella <sgarzare@redhat.com>
Signed-off-by: Raf Dickson <rafdog35@gmail.com>
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Reviewed-by: Luigi Leonardi <leonardi@redhat.com>
Reviewed-by: Bobby Eshleman <bobbyeshleman@meta.com>
Link: https://patch.msgid.link/20260612045216.105796-3-rafdog35@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>