Bluetooth: SCO - Fix missing msg_namelen update in sco_sock_recvmsg()

If the socket is in state BT_CONNECT2 and BT_SK_DEFER_SETUP is set in
the flags, sco_sock_recvmsg() returns early with 0 without updating the
possibly set msg_namelen member. This, in turn, leads to a 128 byte
kernel stack leak in net/socket.c.

Fix this by updating msg_namelen in this case. For all other cases it
will be handled in bt_sock_recvmsg().

Cc: Marcel Holtmann <marcel@holtmann.org>
Cc: Gustavo Padovan <gustavo@padovan.org>
Cc: Johan Hedberg <johan.hedberg@gmail.com>
Signed-off-by: Mathias Krause <minipli@googlemail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
void sco_disconn_cfm(struct hci_conn *hcon, __u8 reason)
{
	BT_DBG("hcon %p reason %d", hcon, reason);

	sco_conn_del(hcon, bt_to_errno(reason));
}

void sco_disconn_cfm(struct hci_conn *hcon, __u8 reason)
{
	BT_DBG("hcon %p reason %d", hcon, reason);

	sco_conn_del(hcon, bt_to_errno(reason));
}
