rxrpc: Fix some missing _bh annotations on locking conn->state_lock

conn->state_lock may be taken in softirq mode, but a previous patch
replaced an outer lock in the response-packet event handling code, and lost
the _bh from that when doing so.

Fix this by applying the _bh annotation to the state_lock locking.

Fixes: a1399f8bb0 ("rxrpc: Call channels should have separate call number spaces")
Signed-off-by: David Howells <dhowells@redhat.com>

net/rxrpc/conn_event.c

@@ -340,18 +340,18 @@ static int rxrpc_process_event(struct rxrpc_connection *conn,
 			return ret;
 
 		spin_lock(&conn->channel_lock);
-		spin_lock(&conn->state_lock);
+		spin_lock_bh(&conn->state_lock);
 
 		if (conn->state == RXRPC_CONN_SERVICE_CHALLENGING) {
 			conn->state = RXRPC_CONN_SERVICE;
-			spin_unlock(&conn->state_lock);
+			spin_unlock_bh(&conn->state_lock);
 			for (loop = 0; loop < RXRPC_MAXCALLS; loop++)
 				rxrpc_call_is_secure(
 					rcu_dereference_protected(
 						conn->channels[loop].call,
 						lockdep_is_held(&conn->channel_lock)));
 		} else {
-			spin_unlock(&conn->state_lock);
+			spin_unlock_bh(&conn->state_lock);
 		}
 
 		spin_unlock(&conn->channel_lock);