rxrpc: Fix rxrpc_bundle::alloc_error to be signed

The alloc_error field in the rxrpc_bundle struct should be signed as it has
negative error codes assigned to it.  Checks directly on it may then fail,
and may produce a warning like this:

	net/rxrpc/conn_client.c:662 rxrpc_wait_for_channel()
	warn: 'bundle->alloc_error' is unsigned

Fixes: 245500d8 ("rxrpc: Rewrite the client connection manager")
Reported-by Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: David Howells <dhowells@redhat.com>

net/rxrpc/ar-internal.h

@@ -395,7 +395,7 @@ struct rxrpc_bundle {
 	unsigned int		debug_id;
 	bool			try_upgrade;	/* True if the bundle is attempting upgrade */
 	bool			alloc_conn;	/* True if someone's getting a conn */
-	unsigned short		alloc_error;	/* Error from last conn allocation */
+	short			alloc_error;	/* Error from last conn allocation */
 	spinlock_t		channel_lock;
 	struct rb_node		local_node;	/* Node in local->client_conns */
 	struct list_head	waiting_calls;	/* Calls waiting for channels */