[Bluetooth] Handle priority bits in parameter negotiation

The PN response have to return the same value for the priority
bits as in the request. The priority value is now also stored
in the rfcomm_dlc structure and the default value is 7.

include/net/bluetooth/rfcomm.h

@@ -185,6 +185,7 @@ struct rfcomm_dlc {
 	atomic_t      refcnt;
 	u8            dlci;
 	u8            addr;
+	u8            priority;
 
 	uint          mtu;
 	u8            v24_sig;

net/bluetooth/rfcomm/core.c

@@ -306,6 +306,7 @@ static int __rfcomm_dlc_open(struct rfcomm_dlc *d, bdaddr_t *src, bdaddr_t *dst,
 
 	d->dlci     = dlci;
 	d->addr     = __addr(s->initiator, dlci);
+	d->priority = 7;
 
 	d->state    = BT_CONFIG;
 	rfcomm_dlc_link(s, d);
@@ -741,7 +742,7 @@ static int rfcomm_send_pn(struct rfcomm_session *s, int cr, struct rfcomm_dlc *d
 
 	pn = (void *) ptr; ptr += sizeof(*pn);
 	pn->dlci        = d->dlci;
-	pn->priority    = 0;
+	pn->priority    = d->priority;
 	pn->ack_timer   = 0;
 	pn->max_retrans = 0;
 
@@ -1099,8 +1100,6 @@ static int rfcomm_apply_pn(struct rfcomm_dlc *d, int cr, struct rfcomm_pn *pn)
 			set_bit(RFCOMM_TX_THROTTLED, &d->flags);
 			d->credits = 0;
 		}
-
-		d->mtu = btohs(pn->mtu);
 	} else {
 		if (pn->flow_ctrl == 0xe0) {
 			d->tx_credits = pn->credits;
@@ -1108,9 +1107,11 @@ static int rfcomm_apply_pn(struct rfcomm_dlc *d, int cr, struct rfcomm_pn *pn)
 			set_bit(RFCOMM_TX_THROTTLED, &d->flags);
 			d->credits = 0;
 		}
+	}
+
+	d->priority = pn->priority;
 
 	d->mtu = btohs(pn->mtu);
-	}
 
 	return 0;
 }