ntb: transport: Fix uninitialized mutex

When the mutex 'link_event_lock' was introduced, it was never
initialized and it triggers kernel warnings when used with locking
debug turned on. Add initialization for the mutex.

Fixes: 3db835dd8f9a ("ntb: Add mutex to make link_event_callback executed linearly.")
Cc: fuyuanli <[e-mail]>
Signed-off-by: Dave Jiang <[e-mail]>
Signed-off-by: Jon Mason <[e-mail]>

drivers/ntb/ntb_transport.c

···
 			goto err2;
 	}
 
+	mutex_init(&nt->link_event_lock);
 	INIT_DELAYED_WORK(&nt->link_work, ntb_transport_link_work);
 	INIT_WORK(&nt->link_cleanup, ntb_transport_link_cleanup_work);