doc, net: Update documentation of synchronisation for TX multiqueue

Commits e308a5d806c852f56590ffdd3834d0df0cbed8d7 ('netdev: Add
netdev->addr_list_lock protection.') and
e8a0464cc950972824e2e128028ae3db666ec1ed ('netdev: Allocate multiple
queues for TX.') introduced more fine-grained locks.

Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Documentation/networking/netdevices.txt

@@ -65,7 +65,7 @@ dev->get_stats:
 	Context: nominally process, but don't sleep inside an rwlock
 
 dev->hard_start_xmit:
-	Synchronization: netif_tx_lock spinlock.
+	Synchronization: __netif_tx_lock spinlock.
 
 	When the driver sets NETIF_F_LLTX in dev->features this will be
 	called without holding netif_tx_lock. In this case the driver
@@ -87,12 +87,12 @@ dev->hard_start_xmit:
 	  Only valid when NETIF_F_LLTX is set.
 
 dev->tx_timeout:
-	Synchronization: netif_tx_lock spinlock.
+	Synchronization: netif_tx_lock spinlock; all TX queues frozen.
 	Context: BHs disabled
 	Notes: netif_queue_stopped() is guaranteed true
 
 dev->set_rx_mode:
-	Synchronization: netif_tx_lock spinlock.
+	Synchronization: netif_addr_lock spinlock.
 	Context: BHs disabled
 
 struct napi_struct synchronization rules