[Bluetooth] Add RFCOMM role switch support

This patch adds the support for RFCOMM role switching before the
connection is fully established.
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

net/bluetooth/rfcomm/core.c

@@ -1150,6 +1150,8 @@ static inline int rfcomm_check_link_mode(struct rfcomm_dlc *d)
 
 static void rfcomm_dlc_accept(struct rfcomm_dlc *d)
 {
+	struct sock *sk = d->session->sock->sk;
+
 	BT_DBG("dlc %p", d);
 
 	rfcomm_send_ua(d->session, d->dlci);
@@ -1159,6 +1161,9 @@ static void rfcomm_dlc_accept(struct rfcomm_dlc *d)
 	d->state_change(d, 0);
 	rfcomm_dlc_unlock(d);
 
+	if (d->link_mode & RFCOMM_LM_MASTER)
+		hci_conn_switch_role(l2cap_pi(sk)->conn->hcon, 0x00);
+
 	rfcomm_send_msc(d->session, 1, d->dlci, d->v24_sig);
 }