Bluetooth: Fix missing retransmission action with RR(P=1)

The Bluetooth SIG Profile Tuning Suite Software uses the CSA1 spec
to run the L2CAP tests. The new 3.0 spec has a missing
Retransmit-I-Frames action when the Remote side is Busy.
We still start the retransmission timer if Remote is Busy and unacked
frames > 0. We do everything we did before this change plus the
Retransmission of I-frames.
Signed-off-by: Gustavo F. Padovan <padovan@profusion.mobi>
Reviewed-by: João Paulo Rechi Vita <jprvita@profusion.mobi>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

net/bluetooth/l2cap.c

@@ -3405,8 +3405,8 @@ static inline void l2cap_send_i_or_rr_or_rnr(struct sock *sk)
 		pi->conn_state &= ~L2CAP_CONN_SEND_FBIT;
 	}
 
-	if (pi->conn_state & L2CAP_CONN_REMOTE_BUSY && pi->unacked_frames > 0)
-		__mod_retrans_timer();
+	if (pi->conn_state & L2CAP_CONN_REMOTE_BUSY)
+		l2cap_retransmit_frames(sk);
 
 	spin_lock_bh(&pi->send_lock);
 	l2cap_ertm_send(sk);